Stalling when put in gear.

[Via Manci]

Started the 230 after being in the garage all winter.  It started right up.  I pulled it out of the garage with no problem and let it idle.  After about an hour I went back to check it out and found that it was overheating.  So I turned it off and let it cool down.  There was steam coming from the expansion tank.  After about 2 hours I tried to start it.  It did not light right off.  But finally I got it started.  Now when I put it into gear, it stalled out.  I have done this at least 15 times and every time it stalls when I put it in gear. What do you think?

Thanks.

Mike 

[mdsalemi]

Let it idle for an hour?  That's way too long and totally unnecessary.
Did you check your coolant level prior to starting it up?  All fluids should be checked before your spring startup, including coolant.
What you are experiencing is either a failure or other problem with the CSS or on earlier cars (230?), I think there is a vacuum dashpot of some type to raise the throttle a bit when  you put it into gear.

I'd be far more concerned first with the coolant and overheating...

[Benz Dr.]

You might want to do a compression test.
A 230SL should idle forever without overheating. However, never leave an old car running while unattended, especialy if it hasn't run in a long time or you aren't sure how well everything is working. The odds of something going wrong are fairly high. 

[ctaylor738]

You should have a constant speed solenoid on the right side of the intake manifold that nudges the throttle linkage to raise the idle a bit when you put the trans in gear.  It is activated by pressure switches on the transmission.  The switches, the wiring, or the solenoid itself can be bad and cause the idle to drop in gear.  If it is working, there is an adjustment to extend the rod to make it more effective.  If it's working properly, the in-gear idle should be maybe 100 rpm lower than P or N.

[ja17]

Most likely a cylinder is not firing. Remove the spark plugs and take a look at them. Maybe try a new set. As Dan suggests a compression check might also help since severely overheating the engine can blow a head gasket and warp the head.