Pagoda SL Group
W113 Pagoda SL Group => General Discussion => Topic started by: n/a on August 18, 2004, 15:44:45
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Hello all,
my 280sl is miss firing on a cylinder but also running rough as well,
I had a classic car mechanic look at it he has ruled out plugs and
leads and thinks valve gap and injectors to make it run on all six
it starts ok on six in morining and when at running temp above 2800Rpm
is O.K. has anybody any answers?
Pagoda Red. P.S where are all the jokes gone?
red kelly
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Could be a vacuum leak at the intake manifold. Once the engine warms up the gap gets bigger and more air leaks in.
Over a certain speed the effects may go away because of the way the fuel and air mix at higher RPM's. Could also be in the IP.
Or , I don't have a clue.
Daniel G Caron
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Hello Red,
You need compression, gasoline at correct mixture and spark for combustion. If you are lacking any of these you will have a miss. Narrow your choices first. A miss at idle can be low copression check it first before you beat your self up on all the other possibilities. Find out which cylinder is missing. If this doesn't show up in a compression check pull plug wires one at a time at idle to find the culprit. (Use special pliars any NAPA store).
It is good to rule out things like spark plugs and cables but make sure you check them. These parts are fairly inexpensive to replace compared to many other items you may be looking at. An ohm meter check on the spark plug cables and popping a new spark plug in is inexpensive and easy. If you are suspicious of an injector, move it to another cylinder a see if the problem moves.
The entire ignition system should be checked if the miss is random.
A miss caused by improper fuel/air mixture is more difficult and you will need to check a lot of things like fuel volume and pressure, injection pump settings, vacumme leaks (thanks Dan), linkage, mechanical problems like valves adjustment, bad cam, etc, etc.
Keep us up to date.
Joe Alexander
Blacklick, Ohio
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quote:
Originally posted by ja17
If this doesn't show up in a compression check pull plug wires one at a time at idle to find the culprit. (Use special pliars any NAPA store).
Joe Alexander
Blacklick, Ohio
Joe,
Can you describe these pliars so I can go get the right tool? I could really use them right now.
Thanks,
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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thanks all, but leads are o.k and when I pull them off one at a time
they miss more and put back on picks up o.k on each pot.
red kelly
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Hello Rod,
These pliers have insulated handles and jaws to prevent shock. Most autopart stores should have them. Often times the jaws are angled also.
Joe Alexander
Blacklick, Ohio
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quote:
Originally posted by ja17
If you are suspicious of an injector, move it to another cylinder and see if the problem moves.
I am suspicious of a bad injector in my car. I've got a miss in #4 because when I use my new spark plug pliars to pull the wire off the plug the engine behavior does not change. If I pull a wire off any other plug the engine almost dies (running on 4 clyinders!). I then swapped the spark plugs and wires between cylinders #3 and #4 and the problem remained with cylinder #4.
I've never removed a fuel injector, what's the proper way to do this and what tools are required?
Looking ahead, my MB 230 SL Spare Parts List shows the MB part number for the injector as 000 078 07 23. The local MB dealer has MB part number 000 078 11 23. Does anyone know the correct Bosch part number? The local MB dealer wants about $118 each. What's a "good" price for injectors?
Thanks,
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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One can swap wires and move plugs and injectors around to narrow down skip problems, but after all is said and done, the best test before any is the compression test.. Once compression is eastablished , then you know what you are working with .
The best is testing compression specs and compression leak-down for each jug..On a leakdown test, you will know if your valves are leaking, are too tight , and which ones ..etc..This test will also give the Tech an idea of overall engine condition ..
Then start your swapping..
Another good tool for these old ignition vehicles is an ignition scope .. I see them on ebay for $40-$50 and once you have one , you will wonder why it took so long to get one
Between the compression test and ignition scope wave forms , you can diagnose all..
and , lastly , get yourself a nice , big vac gauge .. great for playing around with those IP adjustments...
..this is not to say that the plug/wire/injector swappings are not a good DIY tecnique. We use them all the time ...but for perfection sake , with a couple of standard test tools, you can make these 113s singgggggggggggg......
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Just did this on my 280 SE. Swapped everything from a good cylinder to the bad one with no luck. Found two loose injectors in other cylinders in the process and fixed that. The real problem showed up when I checked the valve clearance on the offending cylinder. One of the exhaust valves was so tight it was staying open all the time. Adjusted the rest of the valves while I was in there and she purr's like a kitten now.
quote:
Originally posted by pagoda red
Hello all,
my 280sl is miss firing on a cylinder but also running rough as well,
I had a classic car mechanic look at it he has ruled out plugs and
leads and thinks valve gap and injectors to make it run on all six
it starts ok on six in morining and when at running temp above 2800Rpm
is O.K. has anybody any answers?
Pagoda Red. P.S where are all the jokes gone?
red kelly
Mikey
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Mikey's post is a perfect example....
A comp/leak test would have pin-pointed the tight valve condition right from the get-go.....
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Mikey,
Thanks for the tip.
A Dalton,
I understand what you mean about doing these test, but I can't do them at home. If I move injectors and the problem remains with #4, then it must be a FI Pump, valve, or distributor problem.
How do I swap injectors?
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Rodd - I remove injectors with a crowfoot wrench, the same one that I use for setting valve clearances, 17 mm I believe. They are not in too tight. There's a thin washer beneath the injectors, that sometimes stays behind, so make sure that on installation, there is only one washer beneath each injector.
A. Dalton: how do you use a vacuum gauge to adjust the IP (or maybe I misunderstood what you wrote)?
Cees Klumper in Amsterdam
'69 white 280 SL automatic
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<<A Dalton,
I understand what you mean about doing these test, but I can't do them at home. >>
The main point of my post was to point out the importance of checking the engine compression before swapping out parts..
I do not know why one can not do a simple compression test at home ..
I won't even touch a car for a tune without comp specs.
The remainding parts of the post/test are just mentioned for those interested in fine tune abilities and are not considered as driveway procedures.
As I stated , nothing wrong with searching out a problem by changing known good parts for comparision, but a simple comp test sure does save a lot of swapping and sure does give a solid base for diagnosis... not just for our 113 , but for any make..
We all know the "It's gotta be fuel or spark" , but we never consider the most important basic of the engine - Compression.
So, my preferance is to always start there...mainly cuz I'm lazy.
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<A. Dalton: how do you use a vacuum gauge to adjust the IP (or maybe I misunderstood what you wrote)?>>
A vac gauge is a simple measureing tool that tells one how well the engine is working with the fuel and ignition settings.
Changing any of these settings and the vac efficiency of the engine changes...so, with a little gauge hooked up to the engine intake system, one can get the most effective tuning of their engine by monitoring the vac. [ prob next best monitor to gas analyzer]
Experienced Techs can do these tunings 'BY EAR' and come close , but I use a gauge cuz I like things right ON.
Unlike the compression testing, gage readings take a little knowledge , but if you get one , they come with Instructions and Pic comparison charts to help in understanding what conditions they are displaying.
If you have A Haynes Manual, there is a small section in there on IP setting using the vac gage for a/f mix. Sec 24 , I believe.
I do have some other articles on this, but I am currently in a moving process , so my scanner and equip are not avail at this time , but will be when I settle in.
I will then post that info, just so members can print them out for 113 info/library accumulation...
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quote:
Originally posted by A Dalton
I do not know why one can not do a simple compression test at home ...
Because I've never personally done a compression test or a leak down test before and I don't own any tools to do said tests. I don't even own a timing light, if that tells you anything. I'm just trying to do what I can before enlisting any help from others. If you come to the 2005 Tech Session in Ohio this July, you can come see my garage and how void it is of tools!
How much do the tools for these tests cost? Are the test procedures in the BBB or Haynes manuals? I don't mind trying something new. Everytime I attempt to fix something on my Pagoda, it's a new experience for me.
In the mean time, it looks like I'll be buying a 17mm crowfoot wrench today. And yes, that means I've never adjusted my valve clearance at home either.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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R
Having read some of your replies , I just thought of you as a DIYer.
We have to get some tools in that garage.. a Garage ain't for the car, it's for toooolz.
A compression tester is just a gage tool and short money.. they also come with simple instuctions and once you use it , you will be happy to have one..
Same goes for a vac gage.. cheap and real handy ..you will sometimes see cars with a vac gage right on the instument cluster.
Back when I first learned cars , it was common practice to pull the plugs and drop them in the correct # hole in a board . Then you did a compression test and marked those PSI #s down for each hole..
Doing the compression test once the plugs are out is simply putting the gage in the plug hole and turning the engine over to see how much pressure that piston will attain.
With this info, one can READ the plug and compare each jugs compression spec and get a good idea of how this engine has been running and what condition it is in..
In a tune , a even balance accross both compression specs and plug conditions are what one is looking for. These little test/observations will give you this info..
And a timing light is nice to have to get the spark where spec design would like it to be.
This setting is critical for Mechanical Fuel Injetion and can not be done without one, even for the best ear tuners.
You quite often see these three items sold as a Tune Testing Kit , with all three as a PAK.. again , not big $$$$
Get one .. you will love youself for it..
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A Dalton,
I can see how you might get that impression. My problem is that I have lots of information, but little practicle experience! I've read darn near every post on the W113 Yahoo Group since it was started until this Group was started (3 years). I've probably read about 95% of the posts here. I retain quite a lot of what I read, but I don't have the time/money to make use of it on my car. I just pass the info on to others.
I bought a set of 10 metric crowfoot wrench extensions today. They are the kind to be used with a 3/8" ratchet.
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00904363000
I'll use this tonight (if I get the last of the house painting done!) to swap injectors #3 and #4. If the problem does not follow the injector, then I'll bite the bullet and get the other tune up tools and go that route. My birthday is in a few weeks, sounds like the wife will be buying me an early present!
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Are these the products I need?
Compression Testers
$25 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00902171000
$50 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00947089000
Timing Lights
$35 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00902137000
$50 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00921027000
$70 - http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00921023000
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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quote:
Originally posted by cees klumper
There's a thin washer beneath the injectors, that sometimes stays behind, so make sure that on installation, there is only one washer beneath each injector.
Cees,
Silly question: Can this washer be reused, or is it a crush washer like on the oil drain pan?
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Rodd,
Make sure to re-tighten the injectors, fuel lines and injection pump fittings to the correct torque lbs. I have heard 18 lbs, but have also read in the BBB that it should be 25 lbs.
Does anyone know the correct torque lbs?
Bob
quote:
Originally posted by rwmastel
A Dalton,
I can see how you might get that impression. My problem is that I have lots of information, but little practicle experience! I've read darn near every post on the W113 Yahoo Group since it was started until this Group was started (3 years). I've probably read about 95% of the posts here. I retain quite a lot of what I read, but I don't have the time/money to make use of it on my car. I just pass the info on to others.
I bought a set of 10 metric crowfoot wrench extensions today. They are the kind to be used with a 3/8" ratchet.
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00904363000
I'll use this tonight (if I get the last of the house painting done!) to swap injectors #3 and #4. If the problem does not follow the injector, then I'll bite the bullet and get the other tune up tools and go that route. My birthday is in a few weeks, sounds like the wife will be buying me an early present!
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
bpossel
Memphis, TN.
1971 280SL
1997 E320
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Just a basic Inductive light is all you need . Variable timing lights are not needed for the old style ignitions.
The advantage of having the Inductive pick-up is you never have to pull a plug wire to hook the light up [ it just clamps over the plug wire and senses the voltage through induction]
The first Sears one is perfect.
Another advantage to the induction light is , besides using it to do ignition timing, you can also clamp it over each plug wire and tell if that plug is firing without even pulling a wire or plug. You just look at the lamp for even blinking. So, if one has a skip, you can just go down the line and spot the dead plug/wire in about 10 seconds..
On the comp gage , the first one is good as it has a 14mm hose and a relief valve .. that's all you need ..the others are for many applications , but you do not need that .. a Plain Jane gage like that is fine. There are cheaper ones that you hold a rubber nipple in the plug hole, but that takes another guy/hand to turn the engine while you hold the gage and they tend to POP out with the compression.. so , get that one and you can do it by yourself..
These two tools will give you a good reading on the internals of your engine and the ability to time the ignition to specs along with the ease of spotting the cause of skips without swapping plugs and wires , etc..
I hope you find that your injector suspicions are founded with that swap, but once you have the tools, a quick check for compression and ignition will save you a lot of time on diagnosis..
Good Luck
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quote:
Originally posted by bpossel
Rodd,
Make sure to re-tighten the injectors, fuel lines and injection pump fittings to the correct torque lbs. I have heard 18 lbs, but have also read in the BBB that it should be 25 lbs.
Does anyone know the correct torque lbs?
Bob
Thanks for the tip. I have tried to order the Technical Data Book, which would have this info, but it was backordered and I've not seen it yet.
A torque wrench is something I do own, but seldom have a need for it.
quote:
Originally posted by A Dalton
Just a basic Inductive light is all you need ...
On the comp gage , the first one is good as it has a 14mm hose and a relief valve .. that's all you need .... a Plain Jane gage like that is fine.
OK, I'll get the cheapest ones and learn a new "skill". It should be fun.
I didn't get to the injectors tonight, I just got done painting at 10:30pm and needed to catch up on the computer!
Thanks for the tool suggestions.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Hay Dalton! Time for compression check!
1. Establish main symptom. Start engine, pull spark plug wire boot from spark plug 4 and rough running engine does not change. Pull a boot from any other plug and engine just about dies in 2 seconds. It's a cylinder-specific problem.
2. Completely swap the electrical side (plugs, plug boots, wires) between cylinders 3 and 4. Start engine, same results pulling boots off plugs.
3. Swap fuel injectors (Bosch DC8C45R1) between cylinders 3 and 4. Start engine, same results pulling boots off plugs.
It's not spark, unless there's a problem with the distributor delivering voltage to position 4 on the distributor cap. It's not fuel, unless there's a problem with the F.I. Pump delivering fuel to the #4 cylinder. I'll be buying a compression tester tomorrow on my lunch hour. I'll assume it comes with instructions!
More to come .....
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Yeah..
Now you can see why we do a compression test first..
I suspect you have a tight valve, just like Mickey had further down on this same thread..
You may want to pull the cover a take a peek, but the test is in order...
If comp is good , you are down to possible fuel pump plunger at 4 .
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<<<<I'll assume it comes with instructions!
>>>
It will, but I will give you a couple of tips that it will not have , as they pertain specificly to a 113 comp. test procedure...
Take the wire OFF the CSV, so you do not pour raw fuel into the engine while turning it over to build up the compression.
Take the coil to cap primary ignition wire off the car so it can't start while you are turning it over .
Try to turn the engine the same amount of time [ turns ] for each reading so they are uniform
and , lastley , hold the throttle plate slightly open so the engine can get some air to compress... this one is seldom done, but makes a difference in total reading... many guys think they have a low compression engine all the way across all cylinders cuz they did the test with the throttle plate all the way closed ..which means the engine had to get its intake supply of air from the idle bleed screw . gasp..gasp..gasp...
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Nice tips! Is a compression test done with the engine hot or cold?
Can I use the compression test guage to perform a leak down test, or is that a different tool?
What am I looking for or what should I do when taking the valve cover off and inspecting for a tight valve?
More background
This problem occurred all of a sudden. I drove the car for the second day straight on a long drive (relatively speaking), a little more than 1 hour on the highway each way. This second day I drove to my destination a little faster, about 80 mph. :evil: After the car sat for about 6 hours, I started it and it ran really rough. I drove it anyway and it mostly smoothed out once hot again, but the miss never goes away completly. Of course, it returns every time the car is started cold.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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You can warm the engine a bit ..
I would wait up on the valve cover removal til you get some comp pressure readings.....
Leak test is in conjuction with pressure , but a little different
we can go over that later, too...
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Rodd - I would maybe check/retorque the headbolts. Did you run into high engine temperatures on your 80 mph drive? The leakdown test involves putting air pressure in the cylinders (valves closed) and then using a gauge to measure how long it takes for the air to leak out (hence the term 'leakdown test'), indicating I suppose the condition of the valves/seats and the pistons/rings.
Cees Klumper in Amsterdam
'69 white 280 SL automatic
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No dangerously high engine temps, but maybe slightly above normal (85c to 90c) on longer uphill stretches.
If a valve is "stuck" then I assume it must be stuck wide open, as the cam lobe would have pushed the valve all the way down into the cylinder. Does this mean the piston would have come up and hit the valve and ruined it? If I have a stuck valve, is that a 100% guarantee that I need major cylinder head repair?
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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quote:
Originally posted by cees klumper
Rodd - I remove injectors with a crowfoot wrench, the same one that I use for setting valve clearances, 17 mm I believe. They are not in too tight. There's a thin washer beneath the injectors, that sometimes stays behind, so make sure that on installation, there is only one washer beneath each injector.
I used the 17mm crowfoot to remove the fuel line from the injector. Those things were stuck tight! The injector was 19mm and I used a normal socket for that. No need for an extra deep socket. They required a serious effort to get loose as well. The washers stuck to the injectors this time.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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To borrow a line from history and Hollywood, "Huston, we have a problem."
Here are my compression readings in psi. Keep in mind that I already knew I had a well worn engine with below average compression. I'm on at least the third timing chain and have unkown actual milage.
#1 - 135
#2 - 130
#3 - 135
#4 - 40
#5 - 120
#6 - 140
So, what do I look for when taking the valve cover off? What simple inspections can I do? I will re-torque the head bolts because I've done this before and it's "regular" maintenance.
If I'm going to be removing rocker arms, tension springs, ball studs, valve springs, cones, retainers, etc. (can you tell I opened my parts book?), then I'll be needing expert assistance.
Thanks everyone! Even though I may have a huge expensive fix on my hands, I feel better troubleshooting as much as I can myself. Maybe we can disassemble a 230SL head at the next tech session!
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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You may be jumping to the worst conclusions..
you may just have a tight valve that just needs adjusting.. like Mickeys did..
Take off cover and turn the engine over til you see that both valves
on # 4 are fully closed . This will mean the piston is on the compression stroke. Now, get a feeler gauge and slide it between the cam lobe and the rocker ... If the clearance is too tight , the valve needs to be adjusted so it will be able to close all the way..[ in other words, so the cam does not hold the valve slightly open cuz there is no clearence between the valve and the cam]
The specs are aprox .007 on the exhaust and .004 on the intake..
Report back your findings
Remember , when checking for clearance , it is best done when the cam lobe is facing straight up from the valve .. that way, you know the rocker is on the lowest spot of the cam [ Cam Base Circle]
That is where you need clearance... there is no clearance when the cam lobe is pushing the valve open..
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Oh man, now I need to buy feeler gauges! :D Oh well, the fun continues.....
Would a stuck valve always be stuck in the full open position, or could it partially close and then be pushed open again every time the cam lobe operated it?
If stuck fully open, would the piston contact the valve?
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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<<Would a stuck valve always be stuck in the full open position, or could it partially close and then be pushed open again every time the cam lobe operated it?
It will be open just a tiny bit , not even enough for you to see .
That is why you need valve adjustment to make sure the low spot on the cam is not keeping it from completely closing.
If stuck fully open, would the piston contact the valve?>>
If it were full open , you would have NO compression.. and , yes , the piston would hit it , but only ONCE...
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Remember to set /check your valve clearances with the engine stone cold !!
Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor
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I bought feeler guages today. Supprisingly inexpensive tool! I'm not sure when I'll get to use them, probably the weekend of 11/27.
About the torque of head bolts: I did a search on this forum and I saw where people suggested it with engine cold and others with engine hot. Which should I do for regular maintenance? Also, it's always stated to torque the bolts in the proper sequence. What is this sequence? I have not looked in Haynes or BBB yet, it's probably there. I have seen 70 ft. lbs listed as the proper torque, is that correct?
Many Thanks,
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Tonight I removed my valve cover. Since I had the lead from the coil to the distributor disconnected, and because I am just worried about cylinder #4, I simply used the starter to move the cam lobes. They were not exactly straight up, but close. On the rocker arm closer to the firewall, the .005 guage would fit through, but not the .006 gauge. On the rocker arm closer to the radiator, the .006 gauge would fit through, but not the .007 gauge.
Saturday I will re-tighten the head bolts and do this again. The BBB says to tighten them in 4 steps.
- With the engine cold:
Tighten in specified order at 4 mkp (28.9 ft-lb)
Tighten in specified order at 6 mkp (43.4 ft-lb)
Tighten in specified order at 9 mkp (65.1 ft-lb)
- With the engine hot (80C, 176F)
Tighten in specified order again at 9 mkp (65.1 ft-lb)
This is less than the 80 ft-lb that's been recommended on this Forum, so I checked two other sources:
Glenn's Mercedes Benz Repair & Tune-up Guide says:
Torque spec for 230SL is 8 mkp (58 ft-lb)
Haynes Mercedes Benz 230/25/280 Repair Manual says:
230-series cars use 58 ft-lb cold and 65 ft-lb hot
280-series cars use 72 ft-lb cold and 80 ft-lb hot
I hope this clears up head bolt torque specs for the different cars. I'll be following the BBB specs.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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What size hex drive do I need for the head bolts? They look like about 10mm or 12mm. I want to buy the right tool on my lunch hour today.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Rodd - pretty sure it's 10 mm hex bolts.
Cees Klumper in Amsterdam
'69 white 280 SL automatic
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Rod,
Did you get the 10mm hex?
Couple of points:
The three stage procedure you quoted is for when fitting a new head gasket i.e. when you have had the head off.
For retorqueing the head, the procedure is to loosen each bolt a few turns and retighten to the final setting, following the tightening sequence bolts 1 thru 14.
This should be done with the engine warm (80 degrees C).
I guess you have the earlier BBB for the 230sl and the specs are on page 00-0/27?
Also read the notes on the opposite page 00-0/26, especially note 2) and 4).
Hope this helps.
naj
65 230SL
68 280SL
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Hello Rodd,
Try the hillbilly leak down test it works and requires no expensive testers.
If your compression is down to 40lb in one cylinder (taken with warm eng.), the problem will be obvious. Remove both rocker arms on the low cylinder. If you have a compressor and air hook up hose for the spark plug hole.... connect an air line from the compressor to the cylinder and listen for air leaks. The air will leak off in one of four places 1)exhaust valve (listen for leak at exhaust tail pipes), 2) intake valve (listen for leak at intake with venturi open, 3) broken rings listen for air leak in engine from open oil filler cap, 4)head gasket (listen for air leaking from coolant resivour).
Yes a cylinder head removal and analysis would be great at the tech session.
Joe Alexander
Blacklick, Ohio
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Naj,
I got a set of Craftsman 3/8 inch drive hex head sockets (4mm, 5mm, 6mm, 7mm, 8mm, 10mm) for $12.49, so I hope they are not 12mm bolts!!
Yes, I have the version of the BBB that covers the 230SL and 250SL, not the 280SL. I found the info you mentioned on pages 00-0/26 and 00-0/27. I originally found my info on page 01-4/1. Having read on since then, there is retighten instructions on page 01-4/3, step 36. What a great book!
Since the retightening is to be done with coolant at 80c, I guess I'll be putting the valve cover back on and going for a drive tomorrow (Saturday) morning.
Joe,
An air compressor is yet another tool I don't have (see below).
I hope I have my bad cylinder resolved long before July 30, but I'm always willing to let my car get torn apart for the greater good!
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Hello Rodd,
The head bolts are 10mm allen socket. Be sure to loosen the radiator cap to relieve pressure in the cooling system before beginning the re-torque. Yes the 230-SL uses a lower torque spec than the 280 even though the head bolts are the same diameter and configuration.
Also make sure the valve adjustment is correct on your low cylinder.
A $15.00 air tank (Harbor Freight) can be used instead of a compressor for your leakdown test!
Joe Alexander
Blacklick, Ohio
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Rodd,
After reading all the posts again, I think Joe is right - a leak down test is in order.
Maybe time for Arthur to convey his leak down test lesson ???
quote:
Leak test is in conjuction with pressure , but a little different
we can go over that later, too...
naj
65 230SL
68 280SL
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quote:
Originally posted by rwmastel
Oh man, now I need to buy feeler gauges! :D Oh well, the fun continues.....
Would a stuck valve always be stuck in the full open position, or could it partially close and then be pushed open again every time the cam lobe operated it?
If stuck fully open, would the piston contact the valve?
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
40 psi - Sounds like a burnt exhaust valve on #4. Wheezs?
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I've never seen a stuck valve in a benz engine that was running. The fact that you have some compression tells me it's not stuck open. The valve guide will come loose if the valve stem is grabbing or galling but alloy valve guides are pretty slippery which is why they need very little lubrication.
You can have a burned valve and still have some compression reading because all the air won't leak through before you get some reading on the guage. A compression tester is therefore only useful in relation to a comparison of all cylinders. A leak down tester is more accurate and a vacuum tester is deadly accurate. This is the tool I use for all of my rebuilding. If a hair falls on the valve seat while placing a valve it will show up as a leak - it's that exact.
You WILL remove the head. In fact you might as well plan on a rebuild pretty soon. Fixing the head on an engine with any bottom end wear will often result in a spun rod bearing or broken rings. It's the old saying about weakest link.......
Daniel G Caron
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quote:
40 psi - Sounds like a burnt exhaust valve on #4.
quote:
You can have a burned valve and still have some compression reading because all the air won't leak through before you get some reading on the guage.
Can someone define "burnt valve". Was it left on the stove too long? ;)
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Rodd,
The sealing edge of the valve head literaly burns off and so the valve cannot seal anymore.
One cause of valve burn is not enough valve clearance at the tappett so the valve does not fully close and therefore gets too hot as it is not able to dissipate any heat to the valve seat / head.
Can also burn when too much 'meat' is taken off the valve head when refacing old valves.
Not doubt others here will add to causes of valve burning.
naj
65 230SL
68 280SL
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quote:
Originally posted by naj
Rodd,
The sealing edge of the valve head literaly burns off and so the valve cannot seal anymore.
One cause of valve burn is not enough valve clearance at the tappett so the valve does not fully close and therefore gets too hot as it is not able to dissipate any heat to the valve seat / head.
Can also burn when too much 'meat' is taken off the valve head when refacing old valves.
Not doubt others here will add to causes of valve burning.
naj
65 230SL
68 280SL
Somebody must have a pix of a burnt valve- just a little 'V' at the edge. Don't think his valves were ever adjusted!
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I have a few from a 220SE and the only ones I've ever seen - this isn't common. Only the valve burns away and not the seat which proves the hardness of the seats and also the heat dissapating abilities of the head. The valves are somewhat softer than the valve seats I believe.
I'm not sure what caused this on this engine as it was like this when I bought the car. These cars use manifold injection and all 3 injectors fire at the same time with 2 different sets of 3 runing from only 2 injection elements on a mechanical injection pump. The 230SL engine is really only a highly modified 220SE engine as they're both 127 engines.
The 220SEb was the engine I learned about injection on and it's a lot harder to make one run right than a 113 car. All the injectors have to be matched to within a few PSI of each other or the weakest of the 3 will spray before the other 2. If one is barely working it will burn out valves and could have been the problem here.
I replaced the 2 bad valves and did the head with injector matching. Now it starts and runs better than any car I own.
Daniel G Caron
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One engine I disassembled last year had been rebuilt by a PO and had two or three burnt valves. A small "V" like glennard describes. I will try to post pictures when I get a chance.
Cees Klumper in Amsterdam
'69 white 280 SL automatic
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I'm bringing this thread back from the dead.
Update:
I got back to my car today for the first time since mid-November. To review, I had 40psi compression in #5 cylinder and a low 120psi to 130psi in the rest of the cylinders. I re-torqued the head bolts and adjusted the valves on #5 cylinder. I never got everything put back together until today.
Compression needs to be tested on a warm engine, so I fired her up and went for a short drive. I knew immediately that things were better. After the drive, compression on #5 tested at 105psi. Still very low, but much better.
Outside of an overhaul, what does the Group suggest I do now to improve my compression?
Thanks,
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Rod,
From your update: I am assuming that you did not take the head off.
Form all the other posts some possiblities spring to mind:
[li] Valves on 5 may not be burnt out but are not seating properly[/li]
[li] Above would happen as deposits build up on valves that don't completely shut [/li]
[li] Bent valve or valves [/li]
However you state compression has gone up from 40 to 105 and the rest are around 120 - 130 so your within 15 - 25% of the rest.
In order to improve compression I would....
Take off head.
Remove valves check seats and valves
Clean head and valves inspect valve seats and valves replace if required.
Lap (grind) valves in. Use a little engineers blue to check seal surface on the seat.
and while head is off
Check bores for size and "Ovality". Measure Bore diameter about 2/3 way down with the piston at the bottom of the stroke and 90 degrees apart. Check within limits
How many miles on your car? Might need new piston rings.....
HTH
Malc
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Malc,
Thanks for the advice, it's what I expected but didn't want to hear.
I know I need to do valve work as the car burns oil out the exhaust (blue smoke). Also, I know the bottom end bearings are worn as I had the oil pan off once and removed the bottom half of the front two bearings and they were worn/scored. It would not suprise me if the cylinders were a little oval. Milage on the car is unknown, but the timing chain that was removed last year was not a factory original chain. I'm assuming it's got about 230,000 miles (368,000 km) on it since this is (at least) the second replacement chain and they last about 100,000 miles each. The Euro odometer reads 68,000 km right now, so that also was an input to my guess on the milage.
I'm trying to hold off on a major engine overhaul as long as I can because once I start that, then I'll want to do other things:
- refurbish automatic transmission
- rebalance drive shaft, inspect for worn parts
- replace leaking seal in differential
- refurbish rear axle seals and bearings
- replace full exhaust system
So, should I leave it parked, drive it like it is, or are there some more simple things I can do to improve the health of my engine compression?
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Rodd,
I doubt there is anything you can do to further improve compression without disassembling the engine. I say drive it, but don't flog it hard and keep a close eye on all fluids, and maybe do compression checks every now and then to see if cyl 5 is changing.
George Davis
'69 280 SL Euro manual
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quote:
Originally posted by George Davis
Rodd,
I doubt there is anything you can do to further improve compression without disassembling the engine. I say drive it, but don't flog it hard and keep a close eye on all fluids, and maybe do compression checks every now and then to see if cyl 5 is changing.
Thanks George,
I do plan on changing all fluids next month and doing some other normal maintenance. Monthly compression checks will be in order until a rebuild occurs. Ever since I've owned it, it's rarely been over 4,000 rpm, never past 5,000.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Rod,
Definitely agree with George. Just keep driving the poor old dear, just be gentle!
You would be amazed how long you will keep going as long as it doesn't start to drink both water and oil in excessive quantities
you should be ok
Cheers
Malc
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quote:
Originally posted by Malc
You would be amazed how long you will keep going....
I'm amazed that it's gone this long!
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Pull the engine.
Ship it to Metric Motors.
Pay him $5800 fot a long block.
Reinstall.
Problem(s) fixed.
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Tom says $5800 for a long block, I assume that means you get a reconditioned engine with a cylinder head but none of the plumbing, starter, flywheel, fuel pump etc
Or
You can get down and dirty, make a mess, dribble oil everywhere, and strip the engine yourself. If your really sneaky you can work on parts on the kitchen table, just don't get caught! :)
On a more serious note you know that you only have your self to blame if it goes wrong, you learn more about your car, and you get to keep your original engine
Just a thought
Malc
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Hello,
You both will need to identify the problem of the low compression before you consider fixes unless you decide to go for the for the total rebuild.
Joe Alexander
Blacklick, Ohio
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Anybody try this:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=10398&item=4542322883&rd=1
naj
65 230SL
68 280SL
-
quote:
Originally posted by Tom230sl
Pull the engine.
Ship it to Metric Motors.
Pay him $5800 fot a long block.
Reinstall.
Problem(s) fixed.
Tom,
My engine (and transmission, differential, axels, and steering box) is original to the car. If I were to do this, I would want mine back so I have the right engine number. Preferrably, I would like to rebuild it myself to gain the experience and save the money.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Well, it was just a bit of joke. But yes, Mike at Metric would redo your block & head, check for and weld any cracks, check the tolerences, and genealy put everything right from the valve cover down to the oil pan. He did my 230 engine. Actually, I think his price is more like $4800, but check with him to be sure www.mercedesengines.net or (818) 712-9881.
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quote:
My engine (and transmission, differential, axels, and steering box) is original to the car. If I were to do this, I would want mine back so I have the right engine number. Preferrably, I would like to rebuild it myself to gain the experience and save the money.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
Rodd,
Metric has, in the past, performed mostly exchange engines. If you send him yours (doesn't sound like this will happen tomorrow) you need to make certain they give you the same head/block back, and that they DON'T grind off the serial numbers to replace with their own. This has happened in the past, though we ensured it did not happen with mine.
With JA17 in your neighborhood, it might be something to try...however, Metric (and Noel's in Florida) does engines for a living. They have all the special tools techniques and more experience in engine rebuilding then all of us combined since they do it exclusively. My personal preference is to defer to experience. Add up all the parts costs first to determine just what you might be saving...
Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored