250 Hesitation and Stalling

[rgrewar]

We recently purchased a 250 (1970 we thought although, I have just been told through an MB Forum that 250s were only made until 1968 so we will have to investigate further) and although it runs beautifully when warmed up, it hesitates and often stalls when cold.  It also shakes a fair bit when in neutral - again, mostly when cold.
The local MB dealership mechanics have tried to figure out the problem but have thus far failed to locate the cause of the problem - I don't really think they understand this older car.  Any suggestions on what I might direct them to investigate?
Thanks for the help.
Rory

[Larry & Norma]

A good place to start is to do the linkage tour as described in the tech manual on this site.

[dwahi]

I have a similar problem, but it happens when its warm rather than cold. I have identified the issue (to be confirmed) to be that the choke is not closing and the  mix is still too rich. the plugs were slightly fouled as a result. Ill let you know once it has been back to a garage...

[jameshoward]

If the problem is relatively minor and is at idle, you could try playing with the idle air screw at the intake; it is for fine adjustment. May also be worth checking that the cold start valve is not leaking fuel.

The search function and wiki will throw up info on the latter.

For what it's worth, it took me about 3 attempts at the linkage tour to get the car running properly, but I then hit the sweet spot and it's been excellent ever since. It's more of an art than a science, I would suggest.

[rgrewar]

Thank you all for such great suggestions - I only wish the mechanics at the MB dealership here were as creative in their thinking.  I note all the responses are from UK members - heres to the Brits who are always so willing to help.
Cheers from Canada

[Benz Dr.]

Sounds like the slide valve is stuck in the warm position. When this happens the engine will start but will have a low idle speed that gets better and smoother as the coolant temp rises. Once warmed the engine will run OK.
This condition, while not perfect, is considerably better than having the slide valve stuck in the cold position. The engine will run very rich and won't run well hot or cold due to fouled spark plugs.

[Neil Thompson]

Dwahi and others, I have had success today which may help somewhat, see http://www.sl113.org/forums/index.php?topic=17098.0

Neil