releasing clutch, engine dies

[billhon]

When starting a cold engine it will only idle without  dyeing with the clutch engaged. Releasing  the  clutch instantly causes  engine  to die. Even after warm up releasing  clutch and shifting  into  neutral  at an intersection  causes engine to die but less frequently. It's  a '68 250SL .thanks, Boise Bill

[ejboyd5]

What lubricant do you have in the transmission?

[billhon]

5w-30, oil and filter (oem) just changed And had no effect on problem.....thanks so much for asap reply!

[ja17]

Have someone look for movement at the crankshaft (vibration dampner) when the clutch depressed and released.

[billhon]

Will do, next week, thanks. What about thermostat on fuel injection ?

[georgem]

5w-30, oil and filter (oem) just changed And had no effect on problem.....thanks so much for asap reply!
[/quOisn'tote]

Hang on, doesnt a manual transmission run auto transmission fluid which is much thinner than what you describe - and the filter? Sure you aren't talking about the engine?

[alchemist]

You should have an automatic transmission fluid in the transmission and not engine oil. It sounds that there is something binding with the clutch plate, causing the engine to die. You may need someone to evaluate the clutch function.

[Shvegel]

I don't think it is a clutch problem. Most clutch related problems result in grinding while shifting from neutral(especially into reverse).  When you release the clutch it in effect becomes a solid shaft with nothing to bind. The excess load if that is the case is most likely coming from somewhere else.  Probably from the gearbox fluid being too thick especially in cold weather.  Other than that engine timing and fuel injection setup issues will cause the same issue but that is less likely.

[Jack Jones]

When I first read this I suspected the possibility of excessive end play in the crankshaft.  I think this is what Joe Alexander is hinting at.  

Jack

[billhon]

The transmission bushings and fluids were changed out 10 months ago. They are using a synthetic gear oil. This problem has just started in the last 4 months. Interestingly  it started when the weather got colder. Sorry my last reply I misread so I replied engine oil not transmission. Monday the mechanic will check for movement of the crankshaft as you mentioned. Thanks again for the assistance.

[kampala]

The point that many are trying to make is that these Manual transmissions do not use "gear oil" like many other Manual transmissions.  The Pagoda Manual transmissions use Automatic Transmission Fluid.  Here's an excerpt from our tech manual:

"One thing a lot of owners do not know is that the standard Mercedes 4-spd of that era uses automatic transmission fluid, not engine or gear oil."

[Benz Dr.]

The point that many are trying to make is that these Manual transmissions do not use "gear oil" like many other Manual transmissions.  The Pagoda Manual transmissions use Automatic Transmission Fluid.  Here's an excerpt from our tech manual:

"One thing a lot of owners do not know is that the standard Mercedes 4-spd of that era uses automatic transmission fluid, not engine or gear oil."

A valid point but I doubt that's the problem. The car only dies at idle or when the clutch is released. Sounds like it needs more fuel at idle. 

[billhon]

Problem resolved, mechanic found loose wire from clutch shorting out. Also two switches on tranny replaced. Electronic ignition installed (not related to clutch ) and she idles beautifully at 800 rpms. Also starts perfectly in cold weather and at 47 years old with 140,000 miles has never run better. Fyi, the valves were done at 120,000 miles.

[Benz Dr.]

Interesting. Why would a 1968 250SL have transmission switch gear? This would have been a fairly easy guess if the model and year were lined up.