Cold Starting Valve

[Mpgeslak]

Hi all, I have been having problems getting my 250SL to start and have been reading the Starting
Aid Tour and following the diagnosis instructions.  I have determined that the CSV is getting power, but it only seems to last for a second or two.  Based on the Tour and a bunch of things I have read on the forum, it seems my TTS might be the problem.  If this is the problem, is there anything that can done to repair it or will I need to replace it (from what I see this can be an expensive option). 

Also, can I rule it out it isn’t a problem with the relay?  I have opened it up and cleaned the contacts and done the rest of the tests and everything else checks out other than the power from #87 only lasting a couple of seconds,

Any assistance would be appreciated.

Michael

[ja17]

Hello Michael,  also check the starting solenoid on the injection pump. It should energize whenever the starter is activated.

[wwheeler]

A couple of questions first. You say hard to start. Are you talking about cold, hot or both? How long does it take to start? The CSV should stay on longer if it is really cold. How cold is the engine when you start it? If kept in a climate controlled garage, then that would be the temp inside.

No, you cannot "repair" the TTS. But you can do a ohms test to determine if its working or not. That should be in the tech manual as well.

[Mpgeslak]

Thanks for the responses.

I will check the starting solenoid next, thanks.

It is not in a climate controlled garage and the the temperature is in the low 50’s.  Car will not start at all at this point, so it is a cold start.

Thanks for the responses, have spent a lot of time reading and testing but still can’t figure it out.

[wwheeler]

At 50 degrees, the CSV should stay on much longer than 2 seconds. I would test the TTS and may need to remove it to do so accurately. Not starting at all cold could be a much wider range of problems. I would think a failed starting solenoid would not be the lone fault of the engine not starting. May need to step back to the basics and confirms those - ignition and good fuel flow. Was it doing anything odd before this?

[Pawel66]

Bear inmind you can attach a jumper wire to power your CSV during start to confirm its powering is the root cause of the issue. Please also note that CSV is supposed to be working during warm start as well, it is not just a cold start.

A lot of Members have additional switch to do it while cranking.

[Mpgeslak]

Thanks for the suggestion to step back and go back to basics, I may have gotten my head down following the Starting Aid Tour.

Basics:
Bought the car at auction a couple of months ago.  It didn’t start, I replaced the ignition system with a 123 Electronic Ignition and it started on first turn.  Also replaced the Starter which was failing with a smaller After Market 1.5kw version.  It did start after this, but then stopped.

Battery is charged at 12.6v, getting 10.5v when cranking.  Getting spark to each plug, should note I do have some oil on the threads of plugs. 

The injectors and fuel lines were old and frozen together, replaced both.   Checked fuel flow, which is fine.

Any advice on where to go next?

[Pawel66]

I do not want to side-track you, I am not a mechanic, but if a new or cleaned set of spark plugs does not help, it may be down to fuel delivery issue. The CSV test with a wire is easy - you will see if keeping it activated longer helps.

With 123 - just make sure distributor cap sits ok on the casing, they have weak springs. If the car was running nice, the leads and plug type are ok probably. If you get a nice blue spark - electric side is probably ok. Can always crank it in the dark garage, look for blue "thunders".

Fuel delivery - we measure at the tank end of the return hose (is it how you did it?). Clogged filters (there are 3 or more) or lines, including the return line, often cause starting difficulties.

Do you smell gasoline when you crank a bit longer than usual?

[ja17]

Check the fuel pressure, I would also check the injection  pump rack to make sure it is not stuck.

[Mpgeslak]

Thanks everyone for the advice, very helpful.

Will re-check the distributor cap, I had noticed the clamp is not very tight.  I have not heard the term “blue thunder”, i assume this checking the spark colour for each plug by cranking in the dark?

Will re-check the fuel delivery at the return line.  I do smell fuel when cranking it for a period of time.  How do I check for stuck pump rack, I have researched this but couldn’t find how to diagnose it.

Again, thanks all for your assistance.  With so many variables in the fuel injection/delivery system I am finding it difficult to isolate the issues.

[teahead]

Clean the relay for the TTS.  I.e. open up the box and check the contacts, etc.

BTW, I have a brand new CSV (Bosch) that I'm not using.

Looks like this:

https://www.authenticclassics.com/product-p/auth-003022.htm

[Pawel66]

Sorry for my poor English - by "blue thunder" i meant - when you crank the engine in the dark and there are shorts in the ignition leads, cap or connectors, you may see it as blue sparks between those elements and ground. The good spark on the spark plug should be seen clearly in ambient light.

I had the cap spring gone lose on my 123. It caused cap being lose and this in turn caused broken coal connector between the cap and rotor. Then I heard from other Members about this springs going lose - that is why i wrote about it.

Stuck pump rack - if you go to this link:

https://www.sl113.org/wiki/Fuel/Injection#Pump

and take a look at the first picture under the chapter Operation, you will see where the access is to the pump rack is. The picture does not show the cup that covers this access and needs to be unscrewed. If you have this M4 threaded hole in the tip of the rack, screw in an M4 screw and push the rack backwards gently - it should move backwards with some resistance, but smoothly and then (as it is spring-loaded) it should return. This rack is a toothed bar that moves back and forth causing the Fuel Injection Pump pistons to turn and move. if it is stuck, it means one or more pistons are stuck and are not working. You can try to push the rack in without the screw, but then it may be dificult to pull it back out in case it sticks.

I am enclosing a good guide to work through starting topics systematically, which saves time vs. "shooting from the hip", that even I can understand and follow. Of course not 100% for our cars, but gives a general idea where to start.

[Mpgeslak]

Thanks Pawel for the detailed response.  Will work through the diagnosis step by step on Saturday morning.  Will probably start by going through the set up steps of the new 123 Ignition system I installed.

Just so I am clear on what I see and read on access to the Injector Pump Rack,  can I access it without removing the pump from the car?  From what I see I think I can, but wanted to make sure

Thanks again.

[Pawel66]

Yes, you can access the rack without removing pump. For example look here: https://www.sl113.org/forums/index.php?topic=30088.0

There were a lot of posts about this. Try the search function for FIP for instance.

[Mpgeslak]

I went back over all the basics today, still doesn’t start.  Here is what I found:

Battery:  12.9v and over 10.5v when cranking

Coil: 2 ohms primary resistance, 9 ohms secondary resistance

123 Ignition:  re-checked the set up, all seems fine, only thing I noticed is the rotor has more play in it than I would have expected

Plugs:  seem to get a good spark on all of them.  There is oil on all the threads

Fuel: did the test and got 1 litre of flow in 15 seconds, and which seems good

IP Rack:  I could easily push it in an inch or so and it came right back out

Compression Test:  did a compression test and 4 were low, two down near 40%

My current thinking is the oil change on spark plug threads and low compression means a bigger problem, guessing head gasket?

Thoughts?

[ja17]

Might want to check the valve adjustment to see if all the valves are closing. Remember, if you have spark on time, fuel and compression, it should run.

[Benz Dr.]

Plugged cold start valve.

[Pawel66]

You have some clues here to follow what BenzDr. is suggesting:

https://www.sl113.org/forums/index.php?topic=840.msg4024#msg4024

[Mpgeslak]

Thanks for all the help, The suggestions on the basics of spark and fuel were spot on and I finally figured it out.

I had tested the plugs using an inline tester with a light and they tested fine.  Given I have oil on the plug threads, I got to thinking maybe the oil was stopping them from sparking as well as a simple light test suggested.  So I figured I would look at the spark myself and tested the plugs out of the cylinder and  I found a couple weren’t sparking well.   Since I had already tested the new ignition and it was all fine I cleaned the plugs really well and it started almost immediately.   

Good news it is starting again, bad news is the oil leak is probably worse than I thought. 

I have removed one of the ball studs and the threads were totally dry, plus there doesn’t seem to be oil on the outside in the spark plug well.  I am guessing head gasket?  I have never removed a head before, but I have read the Workshop Manual and searched the forums for information.   

The thing I am most worried about is doing something wrong and making the situation worse.  Thoughts on how big a job it is for someone who hasn’t done it before?

Again, thanks for all the help, it has been fantastic.

Michael

[Mpgeslak]

A bit of an update.  Now that it is starting I have been able to observe more of the symptoms relating to the next problem of oil on the spark plugs.

-  There is grey smoke that gets worse as the car idles
-  the car seems to be idling at a high RPM, but other than that no obvious noises coming from the engine
-  no misfiring
-  I checked the threads again on the ball studs above the spark plug wells and they are all dry. 

What doesn’t make sense to me is how that much oil is getting into the spark plug threads.  I have searched the forum and from what read it seems like the piston rings or the valves.  Suggestions on next steps to diagnose?

Sorry for the newbie questions, thanks again for the help!

[Benz Dr.]

There are three ways oil can get into the combustion chambers: past the rings, down the valve guides or around a loose guide, and more rarely, around an exhaust ball stud. The first two symptoms will show smoke at idle with deposits on the spark plugs. Leaking exhaust ball studs will also produce smoke at idle but the spark plugs will remain clean and dry because oil will only enter the exhaust port and not be burned in the combustion chamber.

[ja17]

If yours is an automatic, smoke can be caused by  a bad modulator diaphragm in the automatic transmission. Top off all fluids and observe. Large amounts of engine and transmission fluids can enter the exhaust manifold and end up in the mufflers. Eventually these fluids will burn off when the exhaust is full temperature. Your problem is find out where the fluids are coming from. A bad head gasket may cause rough running, loss of coolant, smoke and problems maintaining engine temperature.

[wwheeler]

Didn't you say on a few posts back that your compression readings were not very good? I forget, did you ever posts how many miles this engine has?

[Mpgeslak]

Not sure on the mileage as there was no service records with the car.  What I do know is the engine was replaced with another 1967 engine from an SE, but not sure when the replacement occurred.   The mileage is 107k, but no idea how many miles this engine has on it.

The car is a manual.

[FGN59]

Hi,
Once you solve the oil/compression issue, should you wish to replace the TTS, there are several replacement parts (new) on the market, at least in Europe, made by either VDO (the original manufacturer of all the TTSs I have seen) or by Bosch, going for about 70 to 200€:

https://www.theslshop.com/parts-shop/mercedes-benz-r107-350sl-c-w113-thermostat-time-switch-0015459224.html (VDO)
https://www.niemoeller.de/en/search/D%2008%20551 (VDO again)
https://www.sls-hh-shop.de/main/de/mercedes-230-280sl-w113/15-motorelektrik/07-c-elektrische-regulierung/thermozeitschalter-bosch-bauart-siehe-bild-p-134504 (Bosch)

Hard to believe the same part can be found for either 70€ or 200€ from two reputable vendors, so may need to be checked before ordering.

Best of luck with the repairs.

[Pawel66]

This discussion, at this stage, is far ahead of the front line of my knowledge, but I just thought, as you mentioned a potential compression issue, to check if you followed the recommended procedure of doing this.

https://www.sl113.org/wiki/Engine/Compression

[Berggreen]

Hi,
Once you solve the oil/compression issue, should you wish to replace the TTS, there are several replacement parts (new) on the market, at least in Europe, made by either VDO (the original manufacturer of all the TTSs I have seen) or by Bosch, going for about 70 to 200€:

https://www.theslshop.com/parts-shop/mercedes-benz-r107-350sl-c-w113-thermostat-time-switch-0015459224.html (VDO)
https://www.niemoeller.de/en/search/D%2008%20551 (VDO again)
https://www.sls-hh-shop.de/main/de/mercedes-230-280sl-w113/15-motorelektrik/07-c-elektrische-regulierung/thermozeitschalter-bosch-bauart-siehe-bild-p-134504 (Bosch)

Hard to believe the same part can be found for either 70€ or 200€ from two reputable vendors, so may need to be checked before ordering.

Best of luck with the repairs.

Be careful with the two VDO TTS above from the SL Shop and Niemöller. They are not the same spec as the original TTS, because they open at 20C instead of 35C. Also you will need to modify and buy the plug to make it work.

The Bosch has almost the same specs as the VDO, and it works very well - have one installed on my ‘70 280SL. However, as it is somewhat longer than the VDO, and I found that it would not fit in my ‘71 280SL, where the TTS sits in a connector together with coolant tubes to/from the injection pump. In my ‘70 280SL, the TTS sits at the very rear of engine left side, and where is plenty of space for the longer BOSCH TTS.

I do have a surplus of two original VDO TTS, which are both brand new. So, if you (or anyone else) need a new original TTS, then please let me know.

The BOSCH TTS also require a special plug and some re-wirering to work, and I also have wire diagrams I received through communication with the Bosch classic department. Let me know if you want a copy of that as well.

Happy New Year,

Christian :-)

[FGN59]

Hello Christian

I could be interested in one of your original TTS, as the one on my car has unusual characteristics, which I don’t understand:

The car is a 4-speed manual 280SL from late 1968, US model; the TTS bears some of the expected marks: ‘3.03’ for March 2003, ‘35°c +/-3°c’, ‘12V’, ‘120°C.
However there are some which seem a bit unusual: ‘40W’, ‘20°C 5sec’, and ’36/2/9’ right under ‘120°C’.

As you seem to know more about this part than I do, do you have any idea why it is so?

François

[Berggreen]

Hello Christian

I could be interested in one of your original TTS, as the one on my car has unusual characteristics, which I don’t understand:

The car is a 4-speed manual 280SL from late 1968, US model; the TTS bears some of the expected marks: ‘3.03’ for March 2003, ‘35°c +/-3°c’, ‘12V’, ‘120°C.
However there are some which seem a bit unusual: ‘40W’, ‘20°C 5sec’, and ’36/2/9’ right under ‘120°C’.

As you seem to know more about this part than I do, do you have any idea why it is so?

François

Hello François

Yes, the last un-usual markings are indeed un-usual. Normally, a VDO 36/2/9 TTS has the markings 3W and -20°C 9.5sec. Are you sure there is not a "-" in front of the 20°C?

The two new TTS I have are actually 36/2/13's, but they are almost identical to the 36/2/9, except that they have 35°C +/- 4°C instead of +/- 3°C, as well as 40W instead of 3W, like your "odd" 36/2/9.

In any case, I don't think the differences matter. The Bosch also has a switch power of 40W and it works fine with the cold start relay: http://www.bosch-classic.com/en/internet/bosch_classic/produkte/motor_1/thermozeitschalter/thermozeitschalter___mit_teaser_1.html#

What is wrong with the TTS you have?

Which w113 do you have? There are several different generations of cold start systems on the 230-250-280SL.

Cheers,

Christian

[FGN59]

Hi Christian,

Thanks for the quick response and support!

Quickly (sort of):
- I am new to the forum and to W113 cars (but with some experience of old cars and mechanical things)
- 2 months ago I bought a late 1968 280SL US model, reimported from California to Europe about 15 years ago
- the car runs well (I drove it for about 1.000km from Paris to Provence - on smaller roads, taking my time- without any problem and with immense joy
- the car exhibits all the symptoms of a reasonably well tuned engine (temperature, oil pressure, idle regime, absence of smoke or odor at any regime and in any color, acceleration, sound) except cold starts, which are sub-optimal (when I got it, the car started from cold, but only after 10-15 secs of continuous cranking)
- after reading and rereading all possible chapters of the Technical Manual and as many relevant posts as I could find (thanks to all contributors!!!), I investigated and checked everything I could (fuel supply, CSV and CSS relays, TTS, CSV, CSS, wiring harness / electrical connexions)
- there were some small things to be fixed, which I fixed (deteriorated o-ring in CSV solenoid which I replaced), inverted connexions to TTS (G wire to W terminal and W wire to G terminal), and I am really satisfied now that every single component in the cold start mechanism is working as it should; the CSV fires and sprays when it should, the CSS moves the injection pump rack also, the WRD injects air and keeps the injection pump in 'choke' mode until the engine is warm, etc. (as you will see on the pics, I damaged one of the connexions on the TTS while removing it, but I put it back together and verified that it does work according to specs, both in a warm water pan and on the car - not as pretty, but functional...)
- since I fixed the 2 small faults, cold start has improved, but is still not as I would expect from a MB product; sometimes it is almost (but not quite) instantaneous (2-3 secs), sometimes more like 10 secs
- having looked at the spark plugs (the car is equipped with a Dutch(!) 123 solid state ignition), some of which show dark residue build up, I now suspect that perhaps some of the injectors are not spraying as they should, which I will investigate next.

But I also wonder about the somewhat 'strange' TTS on the car (see pictures attached); it is showing '20°C 5 sec', which seems out of range from what I have seen on the forum and on vendors' sites, but I don't understand what would be the reason for this. Could it be that the TTS is adapted to a (really) warm climate, heating up really quickly so that the cold start procedure is shorter and the engine does not flood in warm weather? In which case this is not ideal where I live (we currently have -1°C in the morning, and winter is just starting). But I have not read anything about this anywhere...

A penny (or more ?) for your thoughts? Jokes aside, any idea on the subject would be helpful, if possible... Thank you!

François

[Berggreen]

Hi Christian,

Thanks for the quick response and support!

Quickly (sort of):
- I am new to the forum and to W113 cars (but with some experience of old cars and mechanical things)
- 2 months ago I bought a late 1968 280SL US model, reimported from California to Europe about 15 years ago
- the car runs well (I drove it for about 1.000km from Paris to Provence - on smaller roads, taking my time- without any problem and with immense joy
- the car exhibits all the symptoms of a reasonably well tuned engine (temperature, oil pressure, idle regime, absence of smoke or odor at any regime and in any color, acceleration, sound) except cold starts, which are sub-optimal (when I got it, the car started from cold, but only after 10-15 secs of continuous cranking)
- after reading and rereading all possible chapters of the Technical Manual and as many relevant posts as I could find (thanks to all contributors!!!), I investigated and checked everything I could (fuel supply, CSV and CSS relays, TTS, CSV, CSS, wiring harness / electrical connexions)
- there were some small things to be fixed, which I fixed (deteriorated o-ring in CSV solenoid which I replaced), inverted connexions to TTS (G wire to W terminal and W wire to G terminal), and I am really satisfied now that every single component in the cold start mechanism is working as it should; the CSV fires and sprays when it should, the CSS moves the injection pump rack also, the WRD injects air and keeps the injection pump in 'choke' mode until the engine is warm, etc. (as you will see on the pics, I damaged one of the connexions on the TTS while removing it, but I put it back together and verified that it does work according to specs, both in a warm water pan and on the car - not as pretty, but functional...)
- since I fixed the 2 small faults, cold start has improved, but is still not as I would expect from a MB product; sometimes it is almost (but not quite) instantaneous (2-3 secs), sometimes more like 10 secs
- having looked at the spark plugs (the car is equipped with a Dutch(!) 123 solid state ignition), some of which show dark residue build up, I now suspect that perhaps some of the injectors are not spraying as they should, which I will investigate next.

But I also wonder about the somewhat 'strange' TTS on the car (see pictures attached); it is showing '20°C 5 sec', which seems out of range from what I have seen on the forum and on vendors' sites, but I don't understand what would be the reason for this. Could it be that the TTS is adapted to a (really) warm climate, heating up really quickly so that the cold start procedure is shorter and the engine does not flood in warm weather? In which case this is not ideal where I live (we currently have -1°C in the morning, and winter is just starting). But I have not read anything about this anywhere...

A penny (or more ?) for your thoughts? Jokes aside, any idea on the subject would be helpful, if possible... Thank you!

François

Hi François

I suspect that you TTS is actually normal specs, but just that the minus “-“ and a “9.” have been grinded away or just failed being fully stamped into the TTS during production.

However, if the wires have been swapped, the TTS may have been damaged, as it will heat up a lot, if this is done.

But on the other hand, if you have tested it both in warm water and installed, ai guess it should be ok.. But maybe it is not functioning all times due to internal damage?

I would try to install a volt meter on the CSV and check when you start from cold how long time current is sent to the CSV. If you don’t want to have a lot of fuel sprayed into the engine, you can remove the fuse for the fuel pump. Take the wire off the CSV and connect to plus on the volt meter and the frame to minus. Also, remove the connection between the distributor and the coil. Then crank the start key and check if you get current to the CSV and how much and how long. Relate to the engine temperature. If you have -1C at the moment and the car is also this temperature you should get 10-12V for at least 4-5 sec, maybe more. Try several times and maybe wait for some hours and try again to check if you get reliable and the same response.

If all checks out fine, I would aim at the injection if you actually get a uniform spray at all cylinders.

Hope this helps! :-)

Cheers,

Christian

[ja17]

Yes, your system should have a TTS witch activates the cold start valve at 35 C and below. Only the early 230SLs (version II) used a different range and it was 45 C.

[FGN59]

Hello Christian and Joe,

Who said old cars are like the other half of the human race, unpredictable, sometimes annoying, but immensely desirable and ultimately irreplaceable? Or maybe it is the other way around: desirable and irreplaceable, but also unpredictable and sometimes annoying?

Anyway, I tried a variation on Christian's suggestion this morning, ie hooking a test lamp (rather than a volt meter) to the CSV, removing the fuse for the fuel pump and the high voltage wire from the coil to the distributor, and cranking the engine during a cold start. I've done this several times already, in the course of my previous cold start investigations, albeit without the fuel pump fuse removal part. I reasoned that cutting the fuel pump off during the TTS/CSV test might give me new information (even if partial and imperfect) on the status of the injectors (not flooding the cylinders during the dry run test and seeing how the engine started during the actual start after).

The test lamp lit up for approximately 7-8 secs during the dry run (outside temperature was around 5-6°C), meaning the CSV was receiving current for the same amount of time. This confirms my previous tests and conclusion, that the relay and TTS are working more or less as they should (more about the TTS later).

After taking 5mns to put the fuel pump back on line and the high voltage wire in place (coil to distributor), I cranked the engine again for a 'live' cold start (I had left the test lamp in place). This time the engine started literally instantaneously, like in a dream, while the lamp lit up (so TTS and CSV were activated). I then took the car for a short drive around until it had reached its normal working temperature. So I got to enjoy the desirable and irreplaceable parts once again, justifying the small irritations...

All in all, a perfect cold start, after 'dry cranking' for a few seconds (probably not completely dry, I imagine, as there must be some residual pressure in the fuel system, even after a 24hr rest since the last run yesterday?).

This afternoon, after the car had rested for about 3 hours and largely cooled down, I tried to restart it. Same cold start woes as before: about 5-7secs of continuous cranking until the engine finally caught, then normal warm up routine (elevated RPMs, WRD sucking air, then gradually returning to normal idle a the engine gets warmer; this part leads me to believe the WRD is working right too).

Unpredictable? Well, maybe not. After all, except for this morning, the cold start is consistently difficult, yet never impossible. I must not be doing the right thing, that's all (isn't this always the case?).

However, I don't know what to think, and what more to do (isn't this always the case too?). Not ready to give up, but at a loss for the moment...
I have, I believe, explored, tested and eliminated every conceivable malfunction of the cold start system (fuel supply, TTS, CSV, CSS, relays, wiring, fuses), concluding that everything is working as it should. I'm hitting a wall, maybe for lack of knowledge about the injection pump and injectors?

Somebody told me that if the WRD is sucking air forcefully (as mine is), then it is working (ie also sliding the rack in the injection pump). I believe that hearing higher revs (and seeing the RPM counter move up to about 1100) during warmup, followed by a gradual return to normal regime means the WRD is indeed working as it should. Is this purely logical reasoning correct?

I have also been told that if the CSS is activated and working (which it is, as I have tested too), then the injection pump 'choke' mode is activated on cold start. However, I don't know how to test that effectively?

Finally, Christian, could you explain what the mark 36/2/9 (or 36/2/13) on the TTS means? And do you think, from the info I gave here above, that the specs of the TTS on my car are correct for the usage?

With many thanks,

François

[ja17]

Flooding can cause difficult starts also. Try disconnecting each starting aid (one at a time) during your cold starting and see if the problem gets worse or improves.

[Berggreen]

Hi François

Great report in your latest.

One central question: Do you press the gas pendal, when making a "half-cold" start?

If you look in the operation manual for the 280SL, it actually states that you have to press the gas pedal to the floor, when doing a warm or "half-warm" start. Otherwise, you have to crank for a longer period to start the engine. Do you know about this?

If I don't press the gas pedal on my 280SL aut. with a VDO TTS during a "half-warm" start, thus after standing for some hours, I also have(/had - see below) to crack the 5-7 sec. you experience. This is indeed irritating, and 280SL owners also complained about this "warm"-start issue back in those days the 280SL was new. The solution Mercedes offered back then, and which can be found as an optional upgrade in the service handbook (see attached), is to mount a 1s switch, which overrules the TTS and ALWAYS, no matter the engine temperature, will give a 1s burst of fuel with the CSV. The 230SL's actually had this 1s switch installed as standard, but not on the 280SLs.

I have installed this 1s switch in my aut. 280SL, which has a VDO TTS installed. However, on my manual 280SL which has the Bosch TTS installed, I don't need it, as the Bosch TTS already has this 1s CSV burst above 35C implemented in its electronics. Actually, before I changed to the Bosch on the manual 280SL, it already had the 1s switch installed, and I simply moved it to the aut. 280SL, when I installed the Bosch TTS.

So today, I have instant start on both my 280SL's at these otherwise difficult "half-warm" starts.

The 36/2/9 or 36/2/13 do not have any meaning as such, and are just VDO model numbers. There is a small differences between a /9 and /13 TTS, but I don't think it is important, and both can be used in a Pagoda. The most important spec is when the TTS opens, and this has to be 35C and then the 9.5s opening at -20C. The rest of the specs, I don't think is important as long as they are similar.

But, if you cannot get the 1s switch, and want to get rid of the "warm"-start issue, I recommend that you change to the Bosch TTS, because it already has the 1s above 35C burst included in its electronics. The VDO is purely thermo-mechanical and has no electronics to do this, and you therefore have to add the 1s switch instead. However, I think you can get the 1s switch, and I have seen some on Ebay from time to time, and maybe you can actually still buy them new - I think Bosch made/make them. I was so lucky that could just move my 1s switch between my two 280SLs, but maybe somebody else here knows more where to buy them, if you want to stay original and not change the TTS to the Bosch.

Hope this helps!

Cheers,

Christian

[Berggreen]

Flooding can cause difficult starts also. Try disconnecting each starting aid (one at a time) during your cold starting and see if the problem gets worse or improves.

Yes, true Joe, to much fuel can also cause problems.

Actually, if the engine is set up to run a little too rich, you can register a slight difficulty, when doing a really hot start, with the 1s switch installed giving the extra 1s burst with the CSV on top of the normal fuel supply.

So important to tune the engine correctly, when installing the 1s switch or using the Bosch TTS.

Cheers,

Christian

[FGN59]

Thank you both. It feels really good to have help from friendly people who share the same interests!

I will try both Joe's (remove cold start aids one after another) and Christian's (press pedal for half warm starts) suggestions on Sunday (tomorrow I have to go to a funeral  :-(

Have a great week end.

François

[Mpgeslak]

Thanks for the advice, much appreciated.  I have reached out to Colin Ferns in London to deal with the oil in the combustion chamber as this is beyond my skill level.  Will probably be a couple of months before they can get to it. 

Thanks again to everyone for all the great assistance, being a newbie all the information is incredibly valuable.

[FGN59]

Hi everybody,

Time went by, occupied by lots of New Year celebrations and visits; I managed to work only a little on the car here and there, and couldn't find the time to report until today. BUT... my cold start problem is solved, at last.

To quote Sherlock Holmes: once you have eliminated the impossible, whatever remains, however improbable, must be the truth. Having checked and double checked every possible source of failure or non performance of the cold start system, except the cold start valve itself (which I thought I had seen expectorate some fuel early in my verification process, but didn't really check on thoroughly), I went back to it, and found that it didn't work as well as I thought it did. The nozzles were clogged, and only dripped a little fuel, but no spray.

To restore this function, I pulled the nozzle tube out of the cold start valve (tip given by Dr. Benz in another thread, with many thanks), let it soak overnight in carburettor cleaner fluid, put it in an ultrasound cleaner, then heated it slowly (and not too hot) on a bunsen burner, let it cool, put it back in the ultrasound cleaner, cycled several times through this (heat, cool, ultrasound), checking each time on the flow through the nozzles with compressed air. The nozzles eventually came clean, and voilà, the car starts beautifully now.

So in the end I was led, little by little, to perform a complete exploration of this amazing system, resulting at last in restoration of its nominal performance, together with a much better understanding of its makeup and of the role played by its different parts (CSV, TTS, CSS, WRD, enrichment rack on the FIP, fuel delivery, wiring harness, fuse box). I was thus able to correct the wiring for the TTS (G and W wires at TTS end had been inverted when the engine was reinstalled after renovation), identify and correct the absence of the internal o-ring between the CSV solenoid and the CSV itself (destroyed by age and most probably largely responsible for the clogging of the CSV nozzles), and verify that my TTS is working according to specs. I went through this process slowly and clumsily, but it was definitely worth it, for the result obtained and the knowledge gained.

Many thanks again to all who helped, particularly Christian (Berggreen), Joe (ja17), and Dr. Benz, to all those who, collectively and individually wrote the various articles in the Technical Manual, and, last but not least, to Mpgeslak, whose thread I hijacked without even realising it!

The renovation of the window mechanisms awaits now...

Cheers to all, enjoy a good start for the year, as I am.

François