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I just had my pump rebuilt hrough H&R Fuel Injection, so I had to learn more than I cared to learn. Today, I called Hans at H&R (who use to work in the Bosch factory that made these pumps) if it timing was that important. He said timing was very imortant, and that's why he instructed me (as did the book) to set the engine at 20 degress after top dead center when removing the pump. It’s why the pump has notches on the housing to line up the timing. Essentially, Hans said that if the timing was off such that the atomized fuel were to hit a closed valve chamber, the fuel would re-liquify upon contact, resulting in poor combustion. Just like the iginition timing or other timing, some variance is tolerable, its just the degree of variance that perhaps is the discussion at hand. Someone made the point that there pump was 180 degrees off and it ran fine. Someone also suggested that the pump fires twice on each combustion cycle. If this is the case, firing exactly 180 degrees off would not matter, as the pump always fires at 0 degrees and at 180 degrees. I think I have this right, but could be wrong. I am trainable..., or so my wife says... Don't have much more to add, but Hans is the expert on these pumps and how they work in the engine.

Also, why have 6 'pistons' in the fuel injector pump? Logically speaking, I would think you could have the fuel pump feed a simple high pressure continous pump. Yes, the Germans are known to over-engineer, but it seems that 6 fuel lines being fed by 6 plungers in the injection pump would indicate some sort of purposeful design. My $.02.

Achim Ahlert: this isn't Joe either, but Pete is absolutely correct and he is the first among us who brings some light into this confusion about our injection pumps. Our PES 6KL70/120 R whatsoever deliver fuel ndividually to each cylinder (or injector to be exact) and in a discontinuous matter - very related (but not identical) to the 300 SL W198 system. Atomized fuel was only injected through an injector when the intake valve was open, it was not collected over time. You can read all these details in a nice booklet that most of us have - the Owner's manual. Just look into the Technical Reference part. Therefore, Pete is absolutely correct that timing of the pumps matters very well. Furthermore, Bernt, there are no two squirts per one combustion, there is only one. This is the big difference betweeen 220 SE+300 SE early pumps in comparison to our six-plunger fuel injection pumps. Ours turn with half the revolutions of the engine, so, there is only one pump stroke for two engine revolutions (and one cubustion per cylinder) whereas the 220/300SE early pumps turned at the same speed that the engine did/does. I am confused about the fact how many of you pulled already the pump or had it replaced/ remanufactured. It is good common knowledge among the European (or at least German) SL owners that the fuel injection pump itself is mostly the last resort of trouble and is supposed to be a "do not touch" part!! People who know and restore these (there are not many, though) always recommend that first all the other problems with injectors, timing, linkages, distributor, spark plugs etc. - all the things we have been discussing here - should be ruled out before s.o. is concerned about the FI pump. This is a little bit different if the car has sat for a very long time. However, if preowners or other shade-tree mechanics who were not completely skilled with this kind of injection system (and there are not too many either) and already tried to "fix" problems in the past, it is not unlikely that those individuals made things worse.

Tom Sargeant recaps: Achim: you are absolutely correct that these pumps are reliable and should be later on the list in terms of diagnosing performance problems. Tom Cuddy is pretty far down the list, which is why I mentioned it originally and I did not intend to stir such a long discussion. The reason for the need for my pump rebuild is that I broke the flange that secures the housing that holds the thermostat. Don't ask how-I don't want to publicly embarrass myself! Anyway, I decided to pull the whole thing out and have it rebuilt. Glad I did because the car runs great now and looks like new. However, a pump rebuild was not absolutely necessary. What we now have from Joe and Pete is a very nice history about these pumps. We also know that Bernt was correct as relates to an earlier pump on the 220se. Finally, we know that we should be careful in getting the timing correct on these w113 pumps, but that there is some tolerable range of timing around the correct setting that will give adequate performance.

The injector pump migh be your main problem since it is warned by specialists over and over that it must never be allowed to dry out because the pistons can seize. It might be a very good idea to take it to a Bosch shop and have them get it working properly without damage.

Bernt Damm again: Hi all, Ok, I did some more reading and research this weekend on the issue of the FI and timing. Let me elaborate:

1. Yes, the pump should always be installed as per manufacturer's procedures. No doubt about it.
2. The SL is definitely an indirect injection. Look at any specs and you sill see 'Bosch Sechstempel Einspritzpumpe mit Saugrohr Einspritzung'.
3. These systems are a well kept secret because whenever they went for repairs, they always ended up at Bosch directly because of the complexity and special equipment needed. There are today even few people who know exactly how this works, especially the regulation.
4. I checked in some Bosch book of my dad's (He worked with this stuff almost his whole life). I also checked an article in a magazine written in conjunction with Kohler & Schwemmer from Nuremberg in germany. They are the only company in germany that services and repairs these pumps for Bosch. All pumps handed in for repair to any Bosch dealer go there. They said the following, I quote (sort off). 'Beginners and enthusiasts alike are always extremely worried about the injection timing. This is one of the most popular misconceptions as the timing in these systems is not critical at all. This is because the fuel gets injected before the valve and gets ripped into the motor when valve opens or is open. We have proven this often by finding pumps that were installed with timing as far out as a full 180 degrees. Even then, no noticeable change in performance could be noted..."
5. If an engine runs at say 4000 rpm, the valve opens and closes 2000 times a minute and the injector pump injects 2000 times a minute. This means that the injected fuel does not sit and wait for the valve to open, it will be in motion the whole time because of the pulsing air stream in the manifold. It will also not fall down or sit on the walls of the manifold. Mercedes and others had discovered that then already and subsequently changed the injection on later models.
6. There are 6 pistons for the exact dosing of fuel for each cylinder. On the 220SE, there were 2 pistons and 2 distribution pieces with 3 injectors each. They found that it was not possible to get 3 injectors to inject exactly the same amount of fuel if driven from one piston. That was apparently because of tolerances in the injectors etc. They subsequently changed back to the older technology with 6 pistons for that reason.
7. It is also a common misconception to say that fuel injection gives more horsepower than carburetor models. The reason for the higher power is mostly the length and shape of the intake manifold channels that come with it. It has been researched and noted that a longer, straight intake manifold, channels the air to travel faster and easier into the cylinder. This increases the mixture intake and the combustion is more powerful. With all this newly gained information, I still stand with my original point, the FI timing is not important nor will it cause poor performance.

I have also found the following information on the web:

Also: "Pump Timing: Also, about adjusting the pump timing... In my newsgroup wanderings I read two posts at different times. In both posts, they said that the Porsche factory racers found that they could detect no difference in engine performance, no matter how the timing was set. I haven't noticed any difference myself in the adjustment, but I still set it anyway. Just a little tidbit I wanted to pass on." Hope all this enlightens us a little more...

I had a very similar problem on my car. I have an early 1969 280SL. On the rear of my fuel injection pump is a warm start solenoid. This solenoid enriches the mixture only when starting the engine. On my car it was not connected. I wired it to a starting relay and the car starts much better. If you do not have a warm start solenoid on your fuel injection pump, the first thing I would reccommend is a tune up. It is amazing what a difference it can make in starting your car if your ignition system is fresh and properly adjusted. Tow additional items I recently checked include the cold start valve. This valve should only open during cold starts. It is on the intake manifold. If it is leaking it could be dumping additional gas into the system when starting. There is a nut to remove to check and see if it is leaking. This is a real easy test. The second test deal with the fuel injector thermostat. On the fuel injection pump there is a breather filter that air is sucked through when cold. As the engine warms up it should shut down. If it is not shutting down this could lead to a mixture hwich is too lean during a warm start. The test here is to remove the filter while the engine is cold. Star the engine. You can hear and feel the sucking. As the engine warms up the sucking should stop. I just thought of something else, the gas filter. If you have not replaced it recently, try that. I hope this information has been helpful.

Troubleshooting

The injection has been acting up lately. Something is making it run way too rich. It doesn't want to hold the proper fuel mixture settings for more than a couple hundred miles. Anyone have any similar experiences?

The engine almost starts the first few seconds I try each day. It's so close. You think - "if I could just pump the accelerator a couple times it will start". Then it reverts back to just grinding away with no sign of firing except on one cylinder. Will, you suggested the Start Fluid to me a month ago. It still doesn't start using it. Since then I have replaced all the injectors after being told that 5 out of six were not holding any pressure. This car ran GREAT before the front rod bearing let go. I don't think any parts went bad sitting for 3 years. Something is just not connected right. It tries to start the first time you turn the key each day. I have pulled the valve cover to triple-check the timing. IT IS CORRECT and the motor does come close to starting. I've changed coils - looking for a hotter spark. I'm worried that the engine is flooding instead of being starved. Let it sit 24 hours and you get the promising sound of an engine about to fire up. Keep cranking for 2 or 3 minutes and raw fuel runs out of the intake. I'll start looking for a reason for an electrical cut-off or a fuel overload. I read somewhere about a 12 second delay.

Have you tried something as mundaine as double-checking the distributor. When I brought my SL back to life, it took a distributor rebuild to get it to fire. Since you do get some fire, this may not be the issue but worth a thought.

Frank Mallory says: in my experience, the two most important factors in starting these engines are clean, dry spark plugs and a functioning cold start valve (on intake manifold). Even if the pump isn't working, the cold start valve will supply enough fuel to get it started.

Will says: you mention the car wants to start at first then just grinds away. The exact same thing happened to me with the 230 SL. After many frustrating sessions someone mentioned changing the condenser on the distributor. Since it was the only thing I had not changed (since it was almost new) I changed it. The engine cranked right up and ran like nothing was ever wrong. As I said before if it does not light on Starter Fluid or in your case you have raw gas coming out, then you have elimiated fuel starvation. You are on the right track looking for electrical, but I bet it is something simple. I would suggest taking a spark plug and putting it into a plug wire and grounding it, then cranking the engine to see if you have a good spark. The problem I have run into that to our eyes the spark looks good, but in the combustion chamber with the high pressures, the spark weakens. So, be sure to check all the items related to the spark, you’ve done the coil, on to other items.

Will also says, to Frank’s tip: 100% right on the both counts, Frank. I have found that spark plugs will not fire wet and they also can go bad just sitting in an engine for extended period of time. Although it does not make sense, the plugs do not stay useable just sitting in an engine unused.

And Frank goes on: it is possible that the ballast resistor on late 280 SLs was bypassed during starting. On such a car, the ballast resistor is the first thing to check if it runs while the starter is engaged, then stops running when the key is released.

Now that the temperature has gone down into the 30s here in Wichita I have experienced a problem with my 113 that I need some help with. The car starts perfectly cold or warm and when cold or once at operating temperature performs well. However, during the warm-up process, on an intermitent basis the idle drops from 1200 rpm to a stall. Looking at the Haynes manual I believe the Control Valve/Heat Sensor on the fuel injection pump may be the problem. This valve appears to control warm-up air and fuel mix until "turned off" by the warming of the coolant water flowing through the valve. The full warm-up process takes about 10 minutes. I have some questions:

1. Does this Control Valve/Heat Sensor control both the fuel and air mix or just air to the manifold?
2. I presume the valve can get sticky and hang up and if so can I remove and clean the valve or is this beyond user service?
3. What is the relationship between the normal injection pump idle fuel control/ manifold idle air adjustment and the Control Valve/Heat Sensor--in other words how does the normal warm idle speed control process relate to the Control Valve/Heat Sensor during the warm-up period? I presume they must interact in some way during warm-up.
4. Has anyone else experienced this problem and how did you solve the problem?

I live in Southern Oklahoma, but I have some of the same problems in cold weather. About 3 years ago, shortly after I got my 1967 230 SL, I was having some very severe cold weather problems, so I disassembled the Control Valve/Heat Sensor (don't know why it's called it this, as it's really a cold start valve and takes the place of the choke on a carburetor engine.) (Page 72 Fig 3.64 if you're using the Haynes Manual.) To try to answer your questions, yes both Air and Fuel are opened when the engine is cold. The Guide Rod holds the rack open while at the same time, the sliding valve admits additional air into the intake manifold. This air comes through the small air filter on the side of the valve. To check it, remove it when the engine is cold, to see if the engine revs up. It could be plugged. These are available new. If this is not your problem and you decide to go into the valve, you'll have to drain the cooling system to remove the valve. (Refilling and purging all of the air from the system when you refill it is another problem). My car sat idle for many years after being restored and both this sliding control valve was stuck, and also the cold start valve on the intake manifold, which gives it a shot of fuel on first starting. While I had it apart, I took the heat sensor and checked the opening point in a pot of water on the stove. Hold the valve off the bottom with a wire or fork, while stirring the water as it's heating slowly, with an accurate thermometer, determine the full opening temperature (the sliding valve would be fully closed). While it's much better, I almost always have to start it twice in cooler weather, and it'll embarrassingly stall at a stop light, unless it's above 180 degrees. The next step is to add or remove additional "compensating washers" under the assembly. Does anyone know where I can get these?

I have removed the control valve/heat sensor from the car with the help of some penetrating oil and a large screwdriver. The air cleaner when I blow through it is clear, and almost too much so, as if there is no element. I dissassembled the valve to see what was going on. Referring to the Haynes manual Figure 3.64 page 72 there were two washers (item 6) under the heat sensor and none (item 10) under the control valve housing. Upon removal of the (item 7) control valve I discovered a black residue the consistency of grease on the sides of the control valve, presumably and not surprizingly from ingestion of oil fumes and dirt from the engine compartment. It is amazing that this concept can work for long without a cleaner air source. The (item 8) control rod was clean and moves smoothly up and down in the control valve housing. Now comes the bad news. The (item 7) control valve, a small aluminum piston that glides up and down to control the air flow had vertical scoring and for some reason nicks on the gliding surface as though it had had a previous visitor. The "cylinder wall" of the control valve housing looks good. Upon placing the cleaned control valve into the housing and moving it by hand it drags and cants and feels loose in the control valve housing. I do not know the acceptable tolerance on this valve but it may not need to be too tight particularly since it is not lubricated. However, the canting concerns me since this allows the valve to stick and jam. If I just use some emery paper and polish the valve it may not fix the problem since the canting will still occur (too loose in the cylinder). I may call either Pacific Injector or Fairchild Industries and see what they say and find out if I can buy the control valve by itself. I assume we can also get the washer from one of these sources. I have no information on the number of washers or the ratio between air and fuel the washers are to maintain. I have a suspicion this whole assembly is expensive. I did not temperature-check it since I don't think that means much if it is jamming. I guess I will clean it and put it back together for now until I find out more.

Frank says: before taking it (the control valve/heat sensor) apart, did you remove the small air cleaner and check for proper operation of the cold start thermostat & valve by checking vacuum with engine cold and then warmed up? If not, you should check the thermostat in a pan of water to make sure it is functioning. The shims are selected to go with each individual pump and shouldn’t be changed without a good reason to do so. The oval shims will affect the total mixture range, not just warmup mixture.

Since my last post I disassembled the control valve/heat sensor and cleaned the air valve and housing. Some scoreing was evident on the air valve. I tested the heat sensor (by itself) in a pan of hot water on the stove and when heated it moved (extended) 3/16 inch from the fully compressed (retracted position). I took the air cleaner apart and the paper zig-zag element was dirty and needs replacing but was not blocked. I did not change any washers. There are two washers in the control valve and none under the control valve housing next to the injector pump. The operation was more complex than I thought with a spring action inside the control valve/heat sensor and also a spring action inside the fuel injection pump. I reassembled the unit and reinstalled on the car. I could tell it was working because the idle was up around 1500 RPM and I could hear whistling at the air cleaner where I had taken it apart. Upon driving the car the fast idle didn't last too long and the car stalled at idle as before at temperatures between about 120F and 155F. It is hard to tell the exact temperature but it is certainly more than five minutes into warm-up and not at operating temperature yet. Once at operating temperature the car ran and idled fine. In other words I could tell no improvement over before I cleaned the control valve/heat sensor.

Thanks for the warning regarding the effect of the washers on the total mixture range, but I am confused, do you mean both sets of washers impact the mixture or only those inside the control valve? I assume you mean both sets affect mixture. The Haynes manual states "Any adjustment required to bring the switching point within specified range can be made by inserting or removing washers at the control valve housing mating face". Haynes is talking about temperature range (page 72). I believe this means only the washers between the control valve/heat sensor and the injection pump affect temperature. But since I do have not washers there now at that one interface, I am at a loss, unless I can get a higher temperature Heat Sensor and leave the mixture ratio (washers) alone I am not sure there is a fix. I plan to test drive it again once it cold soaks.

Frank then says: sounds OK. The thing to do is put it all back together, then test its operation. It has two functions, increasing idle air (through the filter) and enriched mixture. The air function (as well as overall operation) is tested as I mentioned, by removing the filter, starting the engine, and placing your finger over the air inlet. It should suck strongly when cold, tapering to no suction when coolant reaches about 160 deg. F. To test mixture, remove cap at front of the pump (last of the pumps don't have a cap, test can't be made), screw a long 5mm bolt into end of rack, and test mixture during warmup (VERY SLIGHTLY pull out to richen, push in to make leaner). If either pushing/pulling results in significantly faster idle and smoother running, you should consider adding/ removing washers inside unit (not at base). Add to make leaner, remove to enrichen -- if you need to richen but there are no washers there, I guess you could turn in the little nut at the end of the thermostatic element, but this is normally a no-no. After shutting off the engine (or before starting it), test the rack for freedom of movement by pushing the 5mm screw all the way in and pulling it all the way out. If the rack binds or refuses to return to "neutral"when you release the screw, there is an internal pump problem that will need to be fixed.

I did find the black plastic cap at the front of the injection pump and inserted a 5mm 40mm long bolt and was able to move the "rack" from a neutral detent position out (forward) about 1/2 inch and in (back) about 1/2 inch. In both cases the "rack" returned to the neutral position smoothly and on its own. This was with the engine off and cold. No hangups. I then removed the air cleaner on the control valve/heat sensor (CV/HS) and started the engine (cold soaked overnight ambient 54 degrees F). The engine started quickly, as usual, and significant air flow was going into the CV/HS air inlet. Movement of the bolt out (forward) resulted in a faster idle and smoother running from 0 degrees C to about 70 degrees C. I tested continuously both air intake to the CV/HS and moved the bolt "in" and "out". "Out" resulted in faster idle and smoother running while "in" resulted in reduced idle speed. Movement required was very slight perhaps 1/16 inch, hard to tell exactly. Upon reaching about 80-82 degrees C the air intake had tapered very significantly, but there was still some air intake(small amount) at operating temperature (wear leakage or adjustment??). Movement of the bolt "in" or "out" resulted in an idle reduction in both directions, different from warm up needed enrichment. Therefore during warm-up the engine desires enrichment but at operating temperature is optimized with the present mixture. This would seem to imply that removing washers inside the CV/HS might increase the intake air flow but give more fuel too during warm-up (may result in cancelling each other [air vs. fuel] and result in no enrichment?), but would also result in too rich a mixture at operating temperature. Some questions:

1. How is it we can ignore the normal idle setting controls (fuel screw at the rear of the injection pump and air screw on intake manifold) during these adjustments? Don't they play a part?
2. The books refer to two or three screws on the back of the injection pump (lower range partial load, upper range partial load, full load screw, idle), what do these do and how can we ignore them during this adjustment?
3. I want to understand the total operation of the injection system and adjustments. The books I have (Haynes, Glenns) only tell a little of the story. What books tell the theory of operation and adjustment or is all of this "tribal knowledge"?

Frank in response: that is very good news. To help keep the rack free, it is advisable to remove the side plate and flush out any dirt or gum that has accumulated under there. If the cold start valve is operating properly, it will no longer have any effect on mixture after the engine has reached operating temperature. Normally, the slide completely blocks air coming thru the filter after it extends fully. You can verify that it has fully extended by using a mirror and light to visually check it. If it is closed but the opening is still drawing air, it is because your slide is worn. Buy a new air filter if you are concerned about its effectiveness. I bought one for my 250 SL recently, mostly because I wanted to dress up my pump a little with original yellow cad. This is a complex mechanism and I haven't seen a detailed explanation of its operation -- Section 07-14F of the Service Manual Passenger Cars Starting 1968 is probably the best we have. Anyway, the thing to do is to remove one of the compensating washers inside the unit and see if it doesn't give improved warmup running. I don't know any other way to correct the problem which you have pinned down thru diagnosis.

In your post of Nov 11 you stated the following: "The shims are selected to go with each individual pump and shouldn't be changed without a good reason to do so. The oval shims will affect the total mixture range, not just warmup mixture." In your post today you stated: "If the cold start valve is operating properly, it will no longer have any effect on mixture after the engine has reached operating temperature". I assume you are referring to the control valve/heat sensor and not the cold start valve and that you believe the washers only affect warm-up mixture and not the mixture at operating temperature. I feel your second post is correct and the washers only affect warm-up mixture and not mixture at operating temperature. I appreciate the help you have given me. I wish someone who understood the theory of operation of the entire injection system and its adjustment and troubleshooting would write it all down and put it on the site. I think the injection system is one of the most interesting aspects of these cars yet it seems no one has the whole story.

Frank again: both of my statements are valid in the context in which they were made. The small, round internal shims ("compensating shims") perform a different function than the large, oval shims at the base of the unit. The small shims govern mixture within the warmup cycle, whereas the large shims help govern the overall mixture. You have taken the unit apart without performing diagnosis to determine whether your warmup mixture was too rich or too lean, and I advised you at that point not to change the shims. I didn't feel it necessary to go into a detailed explanation of oval versus round shims at that point.

I've just been putting up with poor cold starting performance. The car only stalls at about 140 -170 deg. F (60 -80 deg C). In warm weather there is no problem. I guess I'm like "Haggar the Horrible", with his leaky roof. Although early in my engineering career I taught Cat Diesel service schools with a similar type of fuel pump/governor, I've never actually been in to this one. I checked my Mercedes manual, but the illustration and operating description are sort of vague. Basically the cold start thermostat valve works on a rocking lever with the altitude corrector (also known as the “barometric compensator”). Thus it does enrich the mixture when cold, by shifting length of control lever vs. the governor/throttle lever connection to the rack. When warm, it extends, giving less fuel for each throttle position. The altitude corrector works in like fashion to this lever, giving less fuel at higher altitudes, or lowered atmospheric pressures. The idle screw on the end of the housing is only adjusted when warm (and of course engine off, since it's adjusting the governor flyweights). This adjustment sets the flyweights against the governor spring for warm idle. The other adjustments you mention are available inside the housing, but should only be set on a calibrated injection bench. The idle air screw setting at the front of the intake manifold adjusts the air/fuel setting on warm idle. There were no washers inside the valve on my assembly. My fuel injection pump had been rebuilt and the valve was not scored or worn, simply slugged. The car had only been run occasionally for almost 10 years (yes, I've also been replacing rubber parts to the chassis.) I did adjust the nuts on the valve (I agree this is a no-no) checking the assembly for the proper opening temp. There were two washers on the bottom, between the housing, and I believe that I need to add another. I examined the injector pump control valve/heat sensor(CV/HS) control valve with a mirror and flashlight at operating temperature and the valve appeared to be all the way closed. In addition Jerry Fairchild (Fairchild Industries) suggested a wear test for the control valve. He stated that there is always some leakage at the air inlet due to the control valve tolerance. However by finger blocking the air inlet, at operating temperature, and noting any variation in idle speed, if the idle varied then valve wear was excessive. I did this test and the idle did not vary, however my idle is up around 1200 rpm and is too high. I think 800-900 rpm is correct. This may have influenced the results some. I did not notice any stalling today so before I remove one of the internal CV/HS washers I plan to just see how the car runs and if it stalls. I asked Jerry if he could buy internal parts for the CV/HS like the control valve itself. He said he could buy a whole new CV/HS assembly for about $1,000 but not the parts (except the thermostat bulb). This is a common story, you can buy the higher level assembly that contains the part you need but not the part itself.

My car stumbles and occasionally stalls when moving from rest. I had the dealer try to solve the stumbling problem. They said everything on the car checks out perfectly, but promised that replacing a "warm operation thermostat in fuel injection system" would solve the problem. $350 later the car behaves virtually the same. The mechanic that worked on the car said that it would always hesitate a little from start-that cars on this vintage don't run the way modern cars do. Now they are saying that they can enrich the mixture, do some more tweaking of the injection system, and maybe a valve adjustment. The stumbling is also what I had on my 280SL, and it was traced to a faulty cold start valve. Later I replaced the entire injection pump and it ran perfectly. So if your mechanic says this is normal, find another mechanic as he is not familiar with the incredibly sensitive IP settings. These old ’60-ies MB's can run so smooth you won’t even know the engine is running. Frank says: could be a lot of things, but first check your injection linkage. It should be without perceptible play and the end of the rod from the throttle should line up with the hole in the pivot bracket. I have a 280 SL question (engine #130-983-12-003813). I am trying to re-start the car after extended dry storage. The fuel was flushed and treated prior to storing. Put new fuel in, the rear pump is getting the fuel to the injection pump, the fuel is getting to the cold start valve, yet no fuel is coming out of the 6 - 1/4" lines feeding the cylinders. Plenty of fuel exits the injection pump to return to the tank. Looking at the manual, it says that I am to push the control rack rod. I am to use a 5mm bolt. Question is that the schematic shows the rod, but I cannot figure out what to do and where to thread this bolt. I believe that the injection valves (could be called something else) may be stuck in the up position thus not allowing fuel to go to the lines. Second question: should I be adding oil into the injection pump if this is a 280?

The later pumps did not have the threaded tap on the rack. Do you have the pump # ? [the last 2 digits], for example R-20. Did you crack open the lines? May be air bound and need bleeding. On the oil question: the 230/250 pumps had an oil reservoir. Yours does not and is lubed from the engine.

Hans Strom: there is quite a small amount of fuel that comes out of the six outlet valves on top of the fuel injection pump, with each pump axle revolution. It does not squirt out like a jet. Therefore, when the fuel lines are empty, it takes a while before they are filled again with fuel, and the injection nozzle gets the necessary pressure built up in order to open up. The reason to try the free movement of the rack is that residue inside can bind the parts. Remove the side plate lid on the pump (under the six outlet valves) and clean out the compartment in there with some solvent.

Frank adds: get someone to crank the engine while you "bleed" the injector lines by opening the connectors at the injection nozzles (i.e., at cylinder head) one at at time, until fuel emerges. Tighten each connector as soon as you see fuel. By the way: did you check your spark plugs? If they are wet, put in new ones.

Thanks for the advice. I took the cover plate off the injection pump and cleaned the inner workings with WD-40 hoping to free whatever might be stuck. Reassembled and tried. Plenty of fuel being delivered to the injection pump, but nothing exiting; except to the return. I tried but nothing coming from the injection pump at all. Any additional suggestions? Could it be possible that the fuel pump does not have the fuel pressure to cause the fuel to go into the lines (probably said this wrong)? Have you experience at testing the flow rate of the pump (in plain terms as I am a novice)?

Will says: The electric fuel pump runs at 11-18 psi and should flow 1.25 gal/min. It still sounds like all the plungers in the mechanical injection pump are stuck and/or the rack is stuck. You can try to unstick things by removing one of the 6 delivery valves screwed into the top of the injection pump body. Flood the inside with WD or spray carb cleaner.

And Frank: look also at the rear of the pump. If you see two large solenoids, disconnect the wires on the lower one.

My engine had been sitting with the fuel lines off the engine and the injection pump disassembled before I attempted to start it today. After a brief (30 second) pressurization of the lines the engine started right up without any bleeding of the fuel lines. I was very surprised to find this, seeing as the injection pump delivers such a small volume of fuel.

Frank: I finally got my ultrasonic cleaner working and tried cleaning a set of injectors that I had pulled out of an old M129 head. Retested them & found they still have poor spray pattern and/or dribble. It doesn't look like these nozzles are rebuildable - has anybody found a shop that can do this? The problem is that some of them appear to develop corrosion on the spray valve or its seat -- either that, or the spring gets weak, so that the spray pattern is irregular and they do not shut off properly. Also, an experienced operator can tell from the sound a nozzle makes when spraying, whether it is good or not.

Will: last time I checked, the injectors were about $100 each and still generally available. As you had mentioned, a faulty injector will not have a correct spray pattern. This leads to loss of power and fuel economy. But worse than those is the possibility the injector is spraying a stream of fuel that is washing down the cylinder walls. I too have a Bosch injector tester. Can you tell me what fluid you use in your tester?

Frank replies: I used Prepsol yesterday, but I think the correct fluid is diesel fuel. Diesel fuel, believe it or not, has more of a cleansing effect than gasoline. I've never had any trouble with my tester.

I just purchased a ‘64 230 SL. It has not been driven in over a year. The gas must be pumped a great deal for the car to start. It was idling at 2500 rpm and was running extremely rich. I tried to adjust the air and the RPM increased to 3500, and still is quite rich. I tried adjusting the fuel on the injection pump. When I pushed the screw in it did not appear that I was able to adjust the fuel. I am thinking the fuel injection system needs a rebuild. Any advice? Is this a do it yourself job or am I better purchashing a rebuilt one?

Mine ran really rich until I cleared the fuel return line, adjusted the thermostat, checked the cold start valve, and cleaned the fuel injectors along with timing the injection pump.

Dan Caron says: the pump isn't something that you can fix yourself. It would need to go to a rebuild center for fixing. It may have a stuck cold start thermostat or a leaking cold start valve which are both things that can be fixed or changed without removal of the injection pump. You should on principle check these things out anyway. If you're that rich you have some fairly big problems. It should be noted that the 230 SL car has its own special injection pump used only on that car and none other. I’ve seen 250 and even 280 pumps on 230 SL's which will pump out more fuel than is needed. Look at the number on the side of the pump and see if you have the right one. I suggest checking the throttle plate (intake manifold butterfly) position and throttle/ injection pump linkage as well. At idle, the throttle plate should be closed and should stick slightly. Idle air (once the engine is warmed up) is controlled by the screw on the front of the manifold, not the throttle plate. With such a high idle speed, I suspect the throttle plate is adjusted open. There is a procedure for basic linkage adjustment which also gets the throttle plate properly adjusted, if you have a manual it should describe it.

I have spent some time under the hood this weekend. On the fuel injection system there is a plate just below where the 6 distribution fuel lines are. It has the number PES6KL70/120R11 then below it has a dig that may have removed a letter followed by U07752. There is some kind of a cap back closer to the trottle with the number EPSJ16P1Z. The return fuel line is not plugged. The throttle plate was closed. The cold start magnet was not engaged. It never engaged. When I put power to it from the battery it easily engaged. What is supposed to control this? On the intake manifold there is some device that has a ground wire and the place for another wire. What is this? Where should it be connected? The linkage down to the throttle was adjusted to hold the throttle open. I suspect this was part of my problem. The car will not run unless I give it enough throttle to hold it at 2,000 RPM - it coughs and backfires. I suspect it is out of time. The distributor cap does not fit tight on the distributor, it can be rotated 1/4 inch. The distributor has a 1/4 inch vertical movement. Do I need to replace the distrubutor or just the cap? The plugs are Autolight AR52 Racing. They are very black (from the rich mixture). The gap is .8 mm (.032in) My book says it should be .35mm (.014 inch)and recommends Bosch W250P21 - is this correct?

I can try to answer a couple of those questions. First, some of the cars have two cold start magnets (solenoids), one on the fuel injection pump and one on the intake manifold. On my car ('69 Euro 280 SL) here's how they work: the magnet on the injection pump is activated whenever the engine is cranked. It is controlled by a relay located on the left side of the engine compartment. The magnet on the manifold is activated when the engine is cranked and the coolant is below 35 degrees C. It is controlled by a relay located next to the relay above, plus a thermo time switch screwed into a housing on the cylinder head. If they aren't getting 12 volts during cranking with a cold engine, it could be the relays or other wiring problems. If the thermo time switch fails, the magnet on the manifold will never work until it's replaced or you wire in a manual bypass switch (that's cheating, but it's easy to do). With a good wiring diagram these circuits are pretty easy to check out. Last, even if the magnet on the manifold is working, the valve inside can be stuck or leaking. There is a basic adjustment for the throttle linkage. Disconnect all of the rods attached to the main control rod that runs across the engine. Make sure the throttle on the manifold is closed and slightly sticking. If there is hole in the linkage bracket on the manifold, align the ball with the hole, (3/8 inch od aluminum tube works great) then adjust the throttle rod so it will hold the main rod in that position and reconnect it. On the other side, make sure the lever on the injection pump moves freely and is in the fully closed position. Adjust the rod so it fits perfectly without moving the main linkage rod. Check now to be sure the throttle and the pump lever begin to move at exactly the same time when the main rod is moved. Last, adjust the short middle linkage rod to connect to the main linkage rod. If your car has progressive linkage, there is a roughly triangular hole in the linkage with a roller inside. Adjust the rod so the roller is all the way to the rear of that triangular hole, but with no tension on it. If this is off, the throttle will be very hard to move with your foot. I'm not sure how it's adjusted on the non-progressive type. I think a little movement of the distributor cap is normal, as long as the alignment lugs are ok. There may also be a little bit of vertical movement of the rotor shaft, but I don't think the entire distributor should move up and down, something is loose or worse if that happens.

I may be a little too early in saying that I fixed my overly rich condition on my 280sl, but following Frank Mallory's advice I removed some adjustment shims from the barometric compensator diaphragm. This unit sits on top of the fuel injection pump and is about 7-8cm in diameter. It pushes down on a lever inside which adjusts fuel mixture over the whole range. With age these compensators wear out and the pin does not push in as far as required. That is why you have to remove some shims to get things back to normal. Unless your car is very obviously running very rich you should first adjust all linkages, throttle baffle, etc. Be sure not to create an overly lean mixture (i.e., check the spark plug reading for typical lean condition signs, also back firing, pinging, etc.) As I understand it these compensators are unfortunately no longer available.

I believe the procedure was posted before, but I can't find it readily - anyway, here's how I checked mine last month: remove the small air filter that is at the back of the FI pump (you will need a skinny wrench) and start the engine when cold. You should hear quite a loud hissing noise from the location where the filter attaches. This means extra air and fuel is being injected as intended. Now refit the filter, run the car to operating temperature and take the fiter off again. The hissing noise should now be gone, indicating that the thermostat has closed properly. If either situation does not occur as described, the thermostat is not working as intended. You can remove the thermostat tower to see whether the thermostat is stuck or is otherwise malfunctioning.

How does one gain access to the shims? Does the barometric compensator unscrew?

Just use a thin 19mm wrench to grab the hex flange at the lower side of the barometric compensator. I took a spark plug reading yesterday and the plug went from very black sooty before to very light, tannish color by removing all three of the thin shims. I may have to ad one again to whether I may be a tad lean now although I have no real indication that it is. Mine was running quite rich (10mpg), but ran strong.

A common cause of a rich mixture across the whole range is a worn barometric compensated for by removing some of the thin shims once you screw it off. Be compensator (the round cylinder on top of the fuel injection pump). This can be careful to check that you don't go to lean by "reading" the plugs after a few test runs. (I got this tip of course from Joe Alexander although I want to make it clear that he may not endorse my possibly pre-mature diagnosis based on this little information).

Bob Smith: About 6 weeks ago my early 250SL was running well and seemed to be giving acceptable, if not good, fuel economy. I looked at the spark plugs and they were clean and dry. Recently…(I remember posting a message about this)I checked the Fuel Injection Pump and it was FULL-TO-THE-BRIM with black sludge. I pumped the SLUDGE out and replaced it with 20W50 motor oil (approx 150-200ml). The following weekend I went for a short trip up the coast, about 154 miles/246KM. My fuel economy went from 12.2 US MPG, (previous weekend trip to the country), down to 8.53 US MPG. I checked the spark plugs again and they (all 6) were covered in black soot. Comments…. I assume that everything worked properly before I changed the oil in the INJ PUMP. Also, no changes have been made to any settings by me or anybody else. I reckon that my idle and running mixture were adjusted with the INJ PUMP full to the brim with THAT BLACK SLUDGE. I have been reading the posts and I saw that there is a GOVERNOR or something in the Fuel Inj Pump. My Questions…. Is it possible that the thick sludge affected the action/movement of the governor? Did you have to make fuel mixture adjustments for RICHNESS after you changed the oil in your INJ PUMP ? OR - Is it something else … maybe the ANEROID COMPENSATOR gone bad. BTW how do I check my ANEROID COMPENSATOR? I can't find anything about it in the BBB or Haynes.

I can tell you that too much oil in the injection pump affects the way to work of the pump. (In my case, it was very difficult to set the CO, idle, etc., until we discovered that oil level of the injection pump was too high). So this is one of the possibilities: If you have adjusted the pump (CO) with the previous oil level, maybe you should adjust it now with the correct oil level. Remember, to read the level of the pump (it should be close to the unique mark of the dipstick):

1. Unscrew the dipstick
2. Clean the dipstick
3. Screw in the dipstick
4. Unscrew the dipstick and read the level

Bernt Damm: Well, the centrifugal weights in the rear of the pump control the 3 dimensional cam position, which controlls the pump rack, which in turn controlls the amount of fuel injected by turning the pistons. The weights work agains 3 sets of springs which come into operation at different rpm levels. If the casing is full of oil, the weights will hit into the oil wich will influence how far they are out or in. If they don't go out far enough, the fuel injected will be less. I would assume that if there is no co-incidence here with some other problem like the starting circuit and valve, that the weights now move out further because they are not hitting oil. Once again, I would advise to check the other possible causes first and then check the idel CO and maybe adjust it on the pump.

Rodd: I did not adjust anything after removing the over-fill of fluid (oil and fuel?) from the Inj. Pump. BUT, I have never tried to fine tune my engine either. It runs without sputter or backfire and gets 16 mpg, so I don't mess with it. The only problem I had with rich running was related to a bad distributor cap not delivering spark. I can replace parts, but I'm not experienced enough to adjust and fine tune things yet. That said, there should be no reason that you can not attain a better fuel mixture and get better fuel effeciency. The problem is that there are so many adjustmets. You need know what to "baseline" first. In the ingition system, there are precise measurements like degrees of advance, dwell, resistance, etc. In the fuel and air system, I think you have to make one basic setting correct and then work you way "out" from there. The experienced people here can help with more details, but I think the concept is that you will have to adjust the main linkage rod that crosses the engine from side to side. You then adjust the parts that connect from that to the Inj. Pump on one end and to the intake manifold and other parts on the other end. Then you keep working on the next connections and so on. With the Inj. Pump itself, there must be something that can be used as a baseline. I'm sure there are ways to test parts of the pump, like movement of the rack, function of the warm-up valve, etc., but I will let other elaborate on those. This is a very complicated device and may need to be sent to a specialist ($$$) for adjustment if your basic tests and adjustments fail to find a problem. Did the fluid re-accumulate in the Inj. Pump?

Bob again: thanks for the info.. I was thinking there had to be something in the INJ pump that was influenced by the oil level. This makes me wonder how the later model pumps with the separate oil supply from the motor maintain their oil level. Rodd, no the oil level has stayed the same since the clean out. I too am not experienced enough yet to make any/many changes to the ignition system or anything else, but as I learn I am sure my confidence level will grow. I didn't make any adjustments to the INJ PUMP, I meant the original adjustments made at the previous service, with it full of SLUDGE. I did empty the SLUDGE out of the INJ Pump and that is when the "rich running" started. Actually I think the fuel system in my car is set up properly. The only change that has been made is the INJ Pump oil level. I could fill the INJ Pump up again with new oil and see how the fuel consumption and richness goes BUT I am trying to have the car working properly. As I don't have a CO meter or pressure gauge,I asked the mechanic at the local garage if he would check the CO level for me. He said "no problems". This is my home work before I have anything done by him. I want him to adjust the CO level and idle speed to be in specs for the car. The BBB says the CO should be 3.5 -- 5.5 % and the idle speed between 700 -800 rpm. I am assuming that there is still adjustment in the Inj Pump. I will keep you informed of the results.

Bernt Damm: I did post about this a while ago. The level on the later pumps is maintained by an overflow hole in the side that bolts to the engine. The oil is fed via a supply line to the pump and the excess overflows back into the engine again. Simple really but dangerous if there is a lot of fuel going into the pump sump because if thins the engine oil and you may never notice it. The CO level of these cars is very high if set up to the specification and you could try and get it a little lower still. How much fuel did and are you using in l/100km ?

Bob again: Hey Bernt,I think I have two issues here:

1. I have changed over to LRP with the same Bosch W6DC plugs that the previous owner used with unleaded fuel and with an additive.
2. The oil level change in the INJ Pump is causing the fuel mixture to be TOO RICH.

In discussions I see others mention using Bosch W7DC or even W9DC plugs. I see that they are "hotter" plugs... what does that mean EXACTLY? I try to mix up my driving between Highway and City (NOT COMMUTING IN TRAFFIC). Using LRP fuel, which Bosch plug is suited to that type of driving? I could change the plugs (relatively cheap) and take the car for a run. I think new, HOTTER plugs, will make a difference but I will still need the exhaust CO level AND FUEL MIXTURE adjusted. What do you think? My consumption was improving slightly:

 21.95 l/100km 13/08/2002 dist. travelled 160.00 km
 19.86 l/100km 15/09/2002 dist. travelled 225.26 Km
 19.39 l/100km 1/10/2002 dist. travelled 187.20 Km
 27.74 l/100km 5/10/2002 dist. travelled 246.40 Km

Thanks for the info about the 280 Inj Pumps, I was just curious.

Bernt: Yes, if enough oil in the pump to foul the regulator, the misxture might be too rich. You should install the plugs or equivalent as recommended by MB. Too cold and they foul up and too hot and you get a hole in the piston. Their face must look the right colour when in use. I don't know about the plug numbers you mention.

Bob again: I recently had a discussion on here about "Sooty Spark Plugs" with many useful responses. Follow-up.... The leads and plug tops all have a maximum of 1K ohm resistance. I changed my plugs from W6DC to W7DC. The distributor has a lot of GUNK (not sure how to describe the crap.. looks granular) in it, but the car has a slight miss. QUESTION... Can I use one of the silicon sprays to clean it with out taking it apart? I don't want to play with the timing etc. ALSO...follow up: the exhaust CO level was 8.3% (Haynes says normal is 3.5--5.5%). The Mechanic looked at my Venturi Inlet and said it was DISGUSTINGLY FILTHY, so he used a pressure can spray called "CARBURETTOR AND THROTTLE BODY CLEANER" which he liberally sprayed around. The black liquid that slithered out eventually turned clear after a second spray. From there he adjusted the fuel mixture down to within specs. While he by-passed my heater core, the motor had a chance to relax. He checked the CO level again because the motor was running roughly. This time the level was 1.5%---- much too lean. He adjusted the level to CO level of 6.3%, slightly above the normal range. One click to the left was too lean. QUESTION... Would the THROTTLE CLEANER SPRAY provide too rich an air supply for the initial adjustment he made? I am now going to drive the car for a couple of weeks and check my fuel consumption. Then I will have the CO level checked again.

Dan Caron: first thing: the W6DC's were way too cold for these engines. Most of the time the 7's are too. He cleaned the throttle valve which is good but all you have is dry air going through there. There's only 3 possible explanations for why it's so slimy. It has a lot of blow by going through there, small crack in the housing allowing coolant to leak in ( I've seen it ) or the CSV is leaking and fuel is backing up into this area. Blow by or leaking are the most common faults. You also need to see if the throttle plate is fully closed. This can me adjusted at the stop screw and should be set so that the throttle valve is just starting to bind when fully closed. You should remove the linkage to do this and then re adjust everything afterwards. If the valve is too far opened it will be hard to get an idle adjustment.

Check the pump thermostat. Sounds like it is not expanding on warmup to shut off extra fuel and air that is needed during cold start and warmup. And … 6.3% is NOT "slightly above normal." Normal is 2 to 3 percent. Twince that is way too much wither for good running and mileage, OR for the environment! At 6 percent you are putting out about twenty times as much CO as a new car.

Bob: Dan, maybe I dramatized the fluid as being slimy.... it was just very black and thick. After it cleared away, the fluid ran clean. That spray produced lots of fumes and I think the first time he adjusted the mixture there was still fumes in the manifold. I will be checking the cold start valve and the throttle valve too. 2-3%--- is that too lean? The MB book suggests a range of 3.5--4.5%. I too am thinking that the Thermostat might need washers removed. That would make it easier to fine tune the CO level. Before doing anything more I will run it for a couple of weeks as I said. My other question was about the dirty distributor. What do you guys think about using one of the silicone sprays to clean it out? I think these sprays are used for cleaning and lubricating electrical components like rheostats in fan switches and dashboard lights etc. anything I suppose. They certainly don't conduct electricity.

I posted a note on an oil leak from the decel solenoid on the back of the FI pump. I spoke to Hans at H&R Fuel Injection. He said that these solenoids frequently leak from the plastic bakelite connector at the end of the solenoid. To correct this:

1. Remove solenoid (4 machine screws);
2. Hold solenoid so that the rod is facing down;
3. Pull the rod in and and out to “milk” the oil out of the solenoid (Seriously-like a cow udder-no kidding);
4. Smoke cigarette
5. Clean solenoid with evaporative solvent (xylene) to get all oil from around the bakelite connection where the leak occurred;
6. Mix 2 part epoxy and run a bead of epoxy around the bakelite end where it connects to metal-creating a seal to keep oil inside.

I was using a good bit of oil (1 quart every 500 miles) that was difficult to explain given the diagnostic specs on my engine and I believe this was the principal source.

Anyone have a quick and dirty solution to adjusting the fuel injection intake? my 66 230 SL is starved for fuel. I pulled the plugs at Walter's suggestion and the plugs look like they are white and dry, which may be contributing to my sluggish take offs and misfires.

First make sure the linkage is correctly adjusted. Incorrect adjustment could easily cause your (apparent) lean condition. The basic linkage adjustment is easy to do, although it may have to be followed by idle adjustment if the throttle plate is incorrectly adjusted. Also check for vacuum leaks, this would also cause a lean condition.

Joe Alexander: Your car is showing the classic symptoms of fuel starvation. First check the fuel filter. If your car is suffering from low fuel pressure or inadequate volume, the fuel filter, electeric fuel pump, the screen in the fuel pump, the screen in the gas tank and the tank itself should be checked. If you can, do a pressure and volume check on the electric fuel pump. You do not want to change perfectly good injection settings if your fuel delivery system is faulty. As posted, the linkages should be checked also. After these items are checked out we can look into the injection. There are many posts on these checks. If still confused or you cannot find the information let us know.

How dirty was the paper fuel filter when you replaced it? Was there any rust or crud in the canister? You can carefully remove the fuel sending unit for the gas tank (in the trunk) and shine a light into the gas tank and see if it has a lot of dirt or rust around the tank screen in the bottom. Be careful of static sparks around gasoline. If your fuel system seems fine we go to the linkage next. One temporary fix for a lean running engine is find a set of NGK #BP6ES spark plugs (try a motocycle shop). They have a wider heat range and will last longer under lean running conditions. However lean running is not good for the engine in the long run. The fuel pump screen is not easiely removed and some early cars do not have it built in the electric fuel pump, so a tank check may be good to try next. I can run down the linkage set up later am going to work now.

The tank is clean and the filter had minimal dirt and debris as I did not know how long the old filter had been in the car. The PO was not the best at maintaining the car so I did it as a precautionary measure. Tom Sargeant sent me a document via email on how to do a minor tune up and I am going to go through the part on the linkage adjustments. As I said yesterday I replaced the spark plugs and gave the FI pump a 1/4 turn counter clockwise and the car takes of *much* better but there is a minor hesitation at 3K RPM's when driving normal (not reving the at a higher RPM) I will head to the garage this afternoon and go through the linkage next. I ordered the Pertronix unit today and I beleve that points system is my biggest issue. It will be a few days till I get it and get it installed. I will let you all know what the results are, I hope they are good.

How likely is a bad fuel injection nozzle the cause of roughness at idle and low revs? I have checked, adjusted and replaced all the other usual suspects...

Dan Caron: if you've eliminated every thing else , I'd say it's fairly likely. Can you list all those things you've done just so I can check them off too?

Here's a list of the major and minor work done since I purchased the car four years ago:

• new engine (Metric Motors rebuild)
• new distributor
• new coil
• crane ignition
• new copper core wires - 1K ends checked w/ multimeter
• timing OK
• replaced warm run thermostat on FI pump
• checked cold start device on manifold for leaks - OK
• cold start solenoid on FI pump is disabled
• adjusted idle mixture
• new plugs - W7dc (medium brown near the spark gap, changing to black closer to the thread area)
• checked for vacuum leaks
• new air filter
• new fuel filter
• checked and adjusted linkage

The idle has always been rough despite the extensive (mostly unrelated) work listed above. The FI pump and injectors are untouched. Have I missed anything?

Dan Caron: change to W9DC and go to the red 26 KV coil with a 1.8 ohm ballast resistor. That'll wake it up. Sorry, but what year is your car? Which distributor did you change to (the number on the housing)?

Joe Alexander: injection nozzle problems are somewhat unusual on these engines. First make sure youre basic tune-up items are in good order. Check the spark plug wires and ends first. It is much more common for a wire end to go bad, creating a miss. You can buy a inexpensive ohm meter for less than $15.00 at Radioshack and measure the ohms resistance. Disconnect the wire at the spark plug and measure the resistance of each wire from the spark plug end to the distributor end of each wire. Compare all wires with the others if any are noticably lower then the plug wire end at the sparkplug or distributor is probably bad. The original solid copper core plug wires do not go bad as a rule. If someone has replaced the plug wires, then, depending on what they used, could also be defective. The spark plug wire ends on the original wire sets and some better replacement sets, unscrew and can be replaced very easily without replacing the whole set. The original sets are very high quality with solid core copper wire and can last forever. The ends may very occasionally fail. Check the compression next. Low compression in a cylinder will show up as an idle miss first. Next isolate the miss to that one cylinder if it is an injector. Move that injector to another cylinder and see if your miss moves to that cylinder!

Dan Caron: never assume that something new is working properly. Do a valve lash check and a compression check. If they look OK then switch two of the injectors from the one that's no working. If the trouble moves to a different cylinder you've found your problem. Note: more than one problem can exist at one time. Although on rare occasions it can be something totally obscure, usually it's pretty obvious when you find it.

Symptom: The car starts easily and runs great...while cold. As soon as the cold start thermostat warms up, the idle slows down until it dies. Adjusting the idle air screw on the manifold does not help. Background: For the longest time I've been struggling with it idling too fast. Eventually figured out that there was a cooling line restriction that was preventing the cold start thermostat from ever getting warm. Now that I've fixed that, I can't get it to idle once it is warm. Question: I suspect that I may have too many washer / shims in the thermostat (as a result of adding them when it didn't warm up anyway). My assumtion is that this will cause it to close too early in terms of engine temperature but not effect the final setting of the FI pump. In other words, I should exprect that I would run through a temperature range where the engine may not idle, but once it is at running temperature I should not have a problem. Is that correct? Or is it possible that too many shims will cause the pump to run too lean after it is completely warm?

Pete Lesler: if it were me, I would buy a new pump thermostat and start with one shim only, then work up to the correct number. I have watched Hans at H&R check the depth of the plunger and add shims, but I don't remember how he did it. It would be great if Bosch made a manual on how to perform these tasks, but I have never been able to find one for sale.

Dan: And you never will either. Bosch doesn't give out any information like that. They will tell tech. specs like how much voltage a coil will produce or spark plug gaps but that's about it. Even if you have the test sheets for an injection pump they're still not much use as you need all the gauges and other equipment to go with it. External adjustments can be made through a trial and error program.

As usual, I wasn't complete in the description of my question. In doing some research to get the terminology straight, I think I answered my own question. In the "warm up device" two different sets of "compensation washers" are identified. One set goes between the control valve housing and the injection pump, the other set goes between the "heat feeler thrust pin" and the "control slide". I have one compensation washer (actually it looks more like a shim as it has the same outline as the housing) between the housing and pump. I have no idea how many compensation washers (these are in fact tiny washers) there are on the thrust pin since at the time I was throwing away good money to a mechanic who I thought knew more than I did. My guess is that he put on quite a few little washers since he did manage to reduce the engine idle even though the warm up device was never getting warm. However, I think that under normal operation the heat feeler should expand until the control slide bottoms out inside the control valve housing. The temperature at which this occurs is adjusted by the small washers on the thrust pin. I probably need to remove some of these washers but I don't think that it will solve my problem since the engine will not idle even when a full operating temperature. Does this make sense?

Pete Lesler: it is my belief that the length of the plunger pin on the thermostat actually increases as the unit heats up, thereby pressing down into the pump. By adding shims, he may have caused an over rich condition. Don't forget, while the engine is warming up you have supplemental air entering the auxiliary air filter at the rear of the pump which compensates for the richness needed to cold start these engines. Does the sucking sound stop at about the same time the engine stalls? I remember replacing my thermostat and checking the thrust of the pin and the one I replaced was a bit shorter and the car ran too rich. Now I could be wrong on this and that's why shims are added to take up the variation of the extended plunger lenght. Anyway, how do your plugs read after you stall out? That may tell a better story. Or can you borrow a portable CO meter?

Joe: it sounds like your warm up unit is working. Assuming your fuel supply is sufficient and your linkages are in order, I would try enrichening the low range of the injection. The knurled knob on back of the injection pump will change the mixture of the engine from idle up to 1700 rpm. The engine must be off to do this. Push inward to engage the slotted screw and rotate clockwise two or three clicks and then see if this helps. Go further if needed. Be sure to keep track of the clicks so you can return to the original settings if needed. Some mechanic may have leaned the pump to compensate for the rich condition caused by that clog in your warm up circuit. Use the big slotted air screw on the intake (Follow small hose from air filter), in conjunction with these pump adjustments, if the idle becomes too fast during the process.

Pete: based on your response that the supplemental air intake shuts down at about the same moment it stalls leads me to check the linkage adjustment of the entire fuel injection system. Is the butterfly throttle valve closing entirely at idle? It is possible that the air throttle remains closed while the linkage to the fuel delivery side of the fuel injection pump is starting to deliver fuel? But, of course, if that were happening, the air idle adjustment should increase the idel when you turn it. Nevertheless I would check out the linkages to see if they are adjusted correctly. You may also wish to check to see if the aneroid compensator has loosened a bit and has backed off. This will also result in a too rich condition. Looks like you are on the right track by checking the fuel injection thermostat. Let us know when you can read your plugs.

This may help to try to reduce the number of variables: bring the engine to operating temp. Unscrew and remove the thermostat from the FI pump (just undo the 2 screws holding the whole unit to the pump, you don't have to undo the water hoses). Measure the total distance from the thermostat mounting surface, to the bottom of the thermostat plunger. Make sure you do this quick enough so that the water temp hasn't lowered too much ( mine was 25.3 mm). Through the opening in the FI pump, measure exactly the distance the plunger (that the thermostat pin acts on) needs to travel to bottom it out. On mine it was 23.2 mm. from the top of the FI pump surface. Calculate the difference between the 2 measurements - mine was 2.1 mm. I then made a 2mm spacer to mount between the thermostat and the FI pump. Now you know that when the engine is at operating temp, the FI pump plunger is in the proper lean position. Remove the little air filter from the FI pump, so that you can easily block the air passage. Now when the engine is warmed up, you can manually close the air passage if it didn't do it automatically. If it then still doesn't run right, at least you've eliminated a couple of items.

If you have checked linkage, ignition timing, and all the obvious other variables, then try increasing the richness at idle by turning the small spring loaded screw at the back of the pump 2-3 turns. See if that helps the idle. If it does, then you were too lean at idle. Then you can either leave it be, assuming you get the idle to return to 850RPM or so and if you can now actually adjust it with the idle air valve, or investigate the thermostat, which still sounds suspect. If you cannot get the engine to richen any more, then I would say the fuel injection thermostat is grossly maladjusted. But whatever you do with these fuel injection adjustments, always return to the starting point if you get no measurable results, or know where the starting point is and how to return to it, as something else is certainly out of adustment.

Oil Supply

Where my injection pump dip stick should be is a 14 mm nut with a slotted top. It appears very difficult to turn. Any insights as to why this slotted nut is where the dip stick should be. Did some dip-stick put that nut there?

Someone must have lost the dip stick. I assume they put a bolt in it's place with a nut to lock it so it would not leak/loosen.

On my car the nut is the dipstick. Took me 7 years looking at the diagrams to figure it out. I could not loosen it with a screwdriver, use a 14 mm socket.

I changed the oil in my 230 SL fuel injection pump. Instead of the T-shaped dipstick, my dipstick was on the end of a 14 mm nut. The nut had a screwdriver slot on the top. Using a window cleaner bottle pump, I was able to pump out 130 ml of old oil. I thought it might of had a slight gasoline smell but the oil didn't look diluted. To replace the oil you need a very small funnel. The small end should have an OD of 7 mm. Measuring the oil taken out and keeping and eye on the dipstick, it turned out to be a relatively easy task.

Will: best way to tell if there is an oil supply to the injection pump is to look at the left side of the block near the front. There is a small cross-section steel line that comes from there and goes to the right side of the injection pump body. This is the oil supply.

Pete Lesler: the fuel injection pump on the 250 SL also used a oil dip stick and a red oil filler cap.

What do you use to suck the old oil out with? And what is the proper amount to put in?

I used a window cleaner bottle pump to remove the oil from the injector pump. On the top rear is a red cap with access to remove and add oil. May be the red cap has been replaced with something else as in my case. I pumped out about 130 ml of dirty oil. I am currently using 20 W 50 in the crankcase and the same in the injection pump. You will need a very small funnel to add new oil to the injection pump. The OD of the small end funner has to be 7 mm. I would get this funnel before I start.

I don't have a red cap on top of the pump, but I do have a metal cap that's about 20-25mm across. I will try the 14mm box end wrench for the dip stick bolt and the spray bottle tool for oil removal. So, you put the oil in through the dip stick bolt hole (7mm) instead of the large hole under the (red) cap on top? It's a shame you can't drain the oil out the bottom. I'll bet there's sludge and junk in the bottom of the housing that the spray bottle pump will not remove. Any way to really clean these pumps out?

I put the oil in the hole under the red cap or where the red cap should be. The hole size there was 7 mm (on my car). Maybe someone else can shed some light on this.

The red plastic cap simply replaced the metal cap of the earlier version. 250 SL had red.

Where did you syphon from, the small dip stick hole or the larger hole on top of the pump? Which hole did you refill through? Do you recall how much you put back in? I haven't removed the dip stick yet, is it accurate right off the bat, or do you have to run the car and measure again? Can you tell I haven't done this before? I'm always nervous messing with something for the first time.

I got a squirt bottle. I got the dip stick out with a screwdriver (no bolt edges, just a screwdriver slot and T-bar). After removing the dipstick I began to clean it. I noticed a driping sound. It was oil running out of the now open hole. When it stopped, there was a puddle on the floor about 12 inches (30 cm) in diameter. I removed the top cap (mine's metal, not red plastic) and began using the pump method. This was not simple due to cramped spacing and I would recommend the siphon method for others. The squirter pump went dry after pumping out 18oz (53 ml) into the bottle. I would say that this was a little overfilled, no? What problems could this overfilled state have caused? Have others found this problem on their cars as well? Once again, if this helps anyone identify how much oil I should put in, my F.I. pump ID Plate says: PES6KL70/120R11 609 33714. I will replace fluid in through the top cap and keep checking the T-bar dipstick for a fill level as I go.

Overfill interferes with the fly-weights at higher rpm fuel metering.

I finally got round to checking the oil level in my 230SL injector pump yesterday. To my surprise, when I took the dip stick out, oil began to run from the hole. The pump was literally full. I sucked all the remaining oil out as far as possible. it was black oil which smelled a lot of fuel. It actually smelled like the old oil I had in the engine when I bought the car. It was thin as water. I sucked out almost 500ml of oil (about 1 pint!) Anyway, the question is which oil should this have and how much? For the time being, I put in about 100ml of SAE30 oil. The dipstick is unforunately showing 'very full' again. I can't get that sucked out because I can't suck hard enough for the thicker oil. This oil in the pump thing seems to be yet another mystery as I could find nothing substantial in any manual about it. Here are some questions:

1. Is the dipstick read when screwed in or when out?
2. How much oil is this supposed to take?
3. What kind of oil is prescribed? They mention engine oil but that could be anything.
4. How often is this supposed to be checked/drained?

There is no drain plug so I assume that Bosch did not intend this to be drained often. Does it fill up by itself over time and if so, with oil from the oil barrier and/or fuel?

Rodd: I struggled with this last year on my 230SL. Mine was overflowing with disgusting black oil as well. I pulled out over 500ml AND there was a large puddle on the floor. I pulled it out using a "squirter" from a window cleaner bottle and squirted it into that bottle. If memory serves me well, I put in about 200ml of the 10w30 "natural" oil that I am using in the engine. This filled it up past the mark on the dip stick, but not to the top of the dip stick hole. It might have been too much, but it was much better than before. On our cars (230SL) the oil does not circulate with anything else, it is a self contained system. I assume the dip stick is measured when screwed in, but not sure. I asked last year about how much oil goes in the injection pump, but I got no difinitive answer. Perhaps someone now with a good MB or Bosch manual can tell us. I would assume any oil that is good for the engine is good for the injector pump. I plan to check mine twice a year for color/odor/consistency. The results of those checks will determine frequency of future checks and changes.

Hans Strom: the fuel injection pump should be filled with good quality engine oil. I use Mobil 1. The amount needed is 0,25 litres (250cc). The level is measured by unscrewing the dip stick, wipe it, and stick it back into the hole, then look at the level. No threading when measuring. The condition you describe with fluid level rising/overflowing are the internal seals leaking petrol into the oil, thus diluting the oil inside the pump. This is bad, due to the rotating parts having to work in too high fluid level, the pump works in an inefficient manner. Means higher fuel consumption, sluggish car. It is potentially disastrous in the long term, because the internal metal parts will wear due to the diluted oil (lubrication becomes unsufficient). And, a worn out injection pump is very expensive to replace. Action: Remove your pump, send it in for service. A plus is, you will then have a freshly calibrated pump to install onto your engine.

The engine does not supply the pump with oil. The engine oil line is used for the oil barrier in the pump only. That is the actual seal between the fuel and oil. There are no other seals as far as I can see. The principle is that the engine oil pressure at the barrier is higher than the fuel pressure and thus prevents fuel form going down into the sump. The barrier is a groove in the pistons and the sleeves of the pump. It is not connected to the sump of the pump. It is sort of like a piston ring made of oil. The only reason I can see for the pump filling up over time is that oil from the barrier grooves leaks down into the sump of the pump. I suppose that this could be normal for a given period of time. I don't know if anyone ever checked this on my car for the past 20 years so I am not worried about it yet. If this happens quickly, then I suspect a problem with the internal pistons and sleeves being worn in the pump. There could also be a problem with the barrier feed pressure or one way valve on the barrier. I suggest that we monitor it and see how quickly it fills up and if it is actually fuel or oil that fills it. If fuel, then I suspect we have a problem with the barrier not working. By the way, MB mentions somewhere in a one-liner that if the pump is too full, the oil pressure of the car must be lowered by shortening the spring in the oil pressure regulator. Suppose that was only true when these cars were new...

Albert: I think there are two different sustems of injection pump on the W 113. The older has an independent oil tank, and the younger uses a common oil circuit with the engine. My Bosch injection specialist mechanic told me that usually, when he checks the oil level in these older pumps, It's necessary to take out oil, due to leaks. This mechanic also told me that a 15/40 engine oil is correct for the pump, and he says that level is read after screw in the dipstick, but Hans Strom has different information. Is anybody sure about this matter? because I think It's very important to have the oil at correct level (just up to the mark), and due to the low capacity of the tank, the difference between "screwed in" and "screwed out" is quite significant. I noticed how important is this oil level, when my mechanic was trying to adjust the CO and other gases With a gas-analysis machine, and it was impossible until we discovered that the oil level was too high.

Where is the dipstick in the 230SL fuel injector pump? I had thought it was under the red screw-on cap, but at least on mine, it isn't. Do I have the wrong cap, or is the dipstick somewhere else?

You have to look at the exact angle to find it. Your cap may or may not have a little "T" handle on it.

Bob Smith: my car is an EARLY, 250 SL, 1967. I wanted to check the oil in my Fuel Injection Pump, so I unscrewed the oil Dip Stick. About 50ml of the blackest sludge poured out of the hole before I could replace it. Since then I have pumped out about 450ml of the same oil. I used a small tube hand pump. Eventually I removed as much of the old oil as possible. When I checked the level with the DIP STICK in the hole, there was little or no oil on it. The entire Injection Pump must have been FULL of SLUDGE. I have replaced the oil with 125 ml of CASTROL GTX2. The Dip Stick has a mark across the flat surface. I assume that is the FULL MARK. When should I check the oil level ? When the motor is hot or when cold?

Rodd: I think you should perform an experiment for us and check it both ways, hot and cold. Let us know if there is any difference. Going by memory, I believe the pump is supposed to hold somewhere around 200ml of oil. This is a guess on my part, so use the dip stick mark for best accuracy. You may want to cosider changing the oil again after 200 miles or so. At that point, any remaining "sludge" should have been blended with the new oil so the second oil change would result in a much cleaner pump. Re-check the level in the pump once per month to make sure it is not rising. If it is, that means fuel is leaking down into the oil reservoir and your pump needs some expensive work.

I just checked in my Haynes manual for the 280SL. I can't see any difference in that pump to my 230SL. They also state to 'check the oil level' I do not believe that this can be self-contained for the following reasons but I don't have a 280 to check. 1: If it (pump) has a dip stick, there must be a reason. Same goes for the filler cap. 2: If it was self contained, the pump housing would be under oil pressure and full to the limit as well. That would be the same problem with the centrifugal weights running into oil. I think this is maybe another of the popular misconceptions. "The pump has an oil line, so it must be self contained". As stated, the pump has an oil line but that is for the oil barrier. If I am wrong on this, I apologize.

Hi all W113 owners with oil dipstick on the injection pump, to avoid doubts about how to mesure the oil level, I have asked directly to KOLLER (Bosch Official Service, and re-builder of these bombs, www.koller.de), in Germany: “The correct oil level is read after screwing the dipstick in”. My mechanic in Barcelona (also Bosch specialist) told me the same.

Hi again, yes, that is Koller und Schwemmer, the company I mentioned in an earlier post. Great to see that they have a website. I just compiled a small list of questions (in german) regarding the injection and sent it off to them. They might not reply since they seem to have a hotline with charges for these questions. Nevertheless, if they do, we will have some 'official' answers.

Engine does not supply the pump with oil on the 230SL. It is a closed lubrication system.

All of the 113 models have an oil line, although only some of the 250's and all of the 280's have no dipstick as they have flow through lubrication. All of the 230 SL's and early 250 SL's have their own oil sump, which needs to be checked periodically, as stated, minor fuel leaks will cause this compartment to get too full. This oil provides a sealing function, but all models mix some of this oil with the fuel to lubricates the fuel injection plungers. The metal to metal clearance in the fuel injection plungers is such that they would bind, with only gasoline, which has almost no lubricity for sliding components. Modern gasoline FI systems use solenoid valves to inject the fuel at the proper time. The fuel pressure of these new systems is provided by the fuel pump (located in the tank in most systems) for proper atomization.

Joe Alexander: in regards to the oiling system on the injection pumps on the 113s; the latter 113 cars were lubricated from the engine via a small metal oil line running between the pump and the engine block. The early versions of this metal line had a check valve in line which prevented backflow of oil or fuel. Mercedes eventually discontinued the checkvalve and even supplied the straight line without the checkvalve for retrofitting to earlier cars. This oil supply also formed the oil barrier or seal for the pump plungers. The oil eventually makes its way to the pump body and seeks the correct level in the injection pump, the excess automatically drains off into the engine via openings in the pump end at the block. Thus the oil level on these pumps is automatically regulated. Also the latter pumps have no dip stick and not even an opening for them. The plungers in injection pumps are fitted into cylinders with extremely close tolerences (millionths!). There are no rings on these plungers. The oil from the engine under pressure forms the seal. Fuel contamination at the fuel pump increases if idle oil pressure of the engine drops below the fuel pressure (9-14 psi.) in the fuel system. At this point fuel will push past the oil seal and collect in the oil in the pump body. On earlier cars with self contained oil injection systems this has greater consequences. In later cars any contaminated oil returns to the engine oil pan and is diluted and hopefully harmlessly burnt off from normal high termperature engine operation. Excessive pump wear, engine wear or extremely low idle oil pressure may aggravate this oil/fuel contamination problem.

Question re FI for 1965 230sl #113-042-10 0011163 ... don't see a dipstick. A 230sl FI should have one, yes? tag on injector body reads: 'Bosch PES6KL70/120R11 503 06480'. Sound correct for 230SL? The oil in there looks really dirty. I can unscrew the breather cap and see an opening about 1cm in diameter. If I can pump old oil out of it, how much to refill? I think that there was a post of 250ml?

Funny, I was looking at my pump today as well, and couldn't find the dipstick either. My car is just a bit later than yours, ser.# 11245, and all our pump nos. match, except my last is: "06530", presumably the ser.# of the pump? - so that makes sense. Now if we could just find the dipstick.

In my Chilton manual it talked about removing a screw on the side of the injector-pump body to check the oil level, so went back to my car to look for that. I found a drain plug immediately left of where the actuator shaft comes out of the pump. It looks like a rear-axle drain plug, and needs an 8mm Allen wrench. I added oil to the hole that is covered by the little breather cap you mentioned earlier. You keep adding ‘till it just starts to dribble out of the drain hole. Mine took about 250ml, so must have been very dry.

I don't know what plug you opened. The dip stick is on the rear end of the F.I. pump (nearest the windshield) and down low. Mine is VERY difficult to see. Feel around for it and look from all angles. It has a flat top with a slot to use a flat-head screwdriver for removal. The stick part inside is only about 30mm long or so.

You added 250ml without draining first? I don't believe these F.I. pumps leak oil often. If anything, fuel would be getting into the oil reservoir thereby filling it up more. Make sure you are opening the correct parts to check for level.

You had me worried - ran straight back out to the car to double-check. I still can't find anything along the top rear surface that might unscrew and hide a dipstick. The only thing that matches your description is screwed into the rear vertical surface of the pump, about 3" above the mixture adjustment screw, but that would mean that the dipstick goes in horizontally, which doesn't make sense. The hole with the little breather cap, and the drain plug i used, are both open to the same reservoir, and seem to be the only logical locations on my pump. Could you take a close-up pic. of the top of your injection pump? The old "picture is worth a thousand words" trick.

This came up a little while back and it seems that the 230 and 250 fi pumps have their own oil supply and therefore a dipstick while the 280 uses engine oil and therefore no dipstick. It may be that your pump is from a newer model. Search back in the archives a month or so ago, there was a good discussion on the subtle workings of these pumps.

I followed the injection pump discussions with much interest, but I am fairly sure i have the original pump. The part numbers seem to jive very well with other cars of about the same serial number. The Chilton manual "MB 1959 -1970" in the "maintenance" section P.36 shows an injection pump with a small filter cap (just like mine) for the filler, and a bleed screw (er, not like mine) to check the level. It may be for other than an SL though. I am definitely open to other ideas, and your suggestion is possible. Maybe a picture will clear up the mystery.

This little dipstick is a real bastard to find the first time. The R11 pump should have the dipstick as far as I can research. Perhaps you need to look again for it. It is located so that you can't see it underneath the cold start solenoid at the rear of the pump. It is nowhere close to the filler cap. The solenoid sits at the rear top of the pump and it is a cylinder shaped protrusion to the rear. Underneath it at a funny angle sits the dipstick. It looks like a little like a wing nut.

It's not along the top at all. It's very low on the pump's "rear-end", below an electrical component.

Naj: level should be upto the mark with dip-stick unscrewed?

Bernt: No, screwed in.

Cees: I am pretty sure it was "screwed in" in our recent discussion on this, because I remember it being different from what I would have expected.

Albert: To avoid doubts about how to measure the oil level, I asked directly to KOLLER (Bosch Official Service, and re-builder of these bombs, www.koller.de), in Germany, and the answer was: the correct oil level is read after screwing the dipstick in. My mechanic in Barcelona (also Bosch specialist) told me the same. Hope this information will help all Pagoda owners with oil dipstick on the injection pump.

Where to get the parts?

Can anyone help in sourcing an injection pump thermostat and thermostat housing?

The source that I use quite a bit for my 230 SL parts is Star Quality in Lagrangeville NY. Phone (914) 223- 5385 or (800) 782-7199. My Catalog list the Thermostat itself (#205-019) for $196 for a 230 SL and $33 for a 250 or 280 SL. Doesn't list the housing & Sliding Valve, but call them.

Well the thermostat is $500!! God knows how much the housing will be if it is no good too.

Does anyone know a source for a secondhand thermostat assembly or is it possible to adapt to the later type of housing and pump?

Will adds: If you are still looking for a 230SL injection pump thermostat and housing I can help. The thermostat is still available from Mercedes, cost is $560. The housings have been rebuilt. But, as an option to the Mercedes thermostat I have a rebuilt thermostat and housing for $620. The only other way to go is to find a complete injection pump and buy it and rob the parts off it you need. FYI, the Bosch number is 141 7230 000 and is currently obsolete from Bosch. As I mentioned previously, it is available from Mercedes. I assume MB gets an exclusive on a Bosch part and we have no choice but to buy it from MB. Good luck and remember, I have a rebuilt unit here for you.

Frank: maybe there are in the same category as 44PHH carbs and other out-of-production parts, that MB gets made on special order. That would account for the high price. Is it possible to adapt the later housing complete with (relatively cheap) thermostat, for use on the 230SL, Will?

Will: I do not know if it is possible to adapt the thermostat from 280 SL injection pump to the 230 SL. We need someone with more knowledge to come forward.

What is the life expectancy of the injector pumps assuming regular oil changes? Can they be rebuilt? Who rebuilds them?

I can't comment on "life expectancy", but I assume it is many, many years. Regarding who rebuilds them, there is a place in California called Pacific Fuel Injection and a place on Long Island (Bohemia, NY) called H&R. According to people on this w113 list, these two places are two of the best in the USA.

I searched high and low and finally found a "tappet wrench" at Sears that was thin-it's a 7/8 inch wrench-vituallly the same as the 22 mm you need, in order to remove the barometric pressure regulator and the air filter on the FI pump.

I was able to remove the air filter with a set of needle-nosed visegrips, without ruining anything.

In the MB manual, the description of replacing the thermostat on the fuel injection unit calls for a material called "Starrit" to seal the thermostat, so that coolant does not leak around it. Does anyone know what Starrit is, and is there an equivalent product available?

I just put a FI thermostat in my car and I used Toyota FIPG(formed in place gasket or in Toyota speak "Fipig") It is one of a new breed of silicone hybrids that are very good general sealers. In fact my entire engine except for the headgasket,valve cover and intake gasket is sealed with it.

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