Shut-off
 

Hi, when turning the key off on my 87 300td the car would not turn off.
The manual shut-off lever does move down from 45 degree up (when car is running normally) to horizontal position when you turn the ignition key off, but it still does not turn the car off (I need to push it manually further down to shut the motor off).
Does this mean that it is definitely a valve that is bad and need to be replaced or it could still be a vacuum problem (like that there is some vacuum which is enough to turn the lever down to horizontal position, but not enough to pull it all the way down)?
I tried disconnecting the vacuum hose from the valve and use the syringe to pull the vacuum to the valve, but had no success (not even to get it horizontal); obviously this is not enough vacuum to test the valve....
Since I do not have a vacuum test kit is there any other simple way to test if this valve needs to be replaced or it is a vacuum leak that I need to look for?
Again; the lever does go down to horizontal when key is turned off; is this a sign that vacuum is OK but actual valve is a problem?

Disconnect all vacuum lines. And run a direct line from the main vacuum to your shutoff

Perfect idea, thanks, will try!

With the engine off, how long before the stop lever goes back to normal position? When it goes down by turning the key to stop the engine, the lever should go down and stay down until you turn the key to glow. Days... weeks, even.

With the engine running, disconnect the hose from the brake booster line to the key switch and hook it up directly to the shutoff actuator. If the engine stops, there's a leak between the vacuum source and the actuator. If the engine doesn't stop and you can't be convinced to obtain a MityVac, try a new shutoff actuator and work back from there.

Sixto
83 300SD

Agreed, mityvac or equivalent to pull vacuum, most likely shutoff actuator or vacuum leak.

OK, did the test by disconnecting all other vacuum tubes from the vacuum pump and connecting just one tube directly to the shut-off valve.
Same result as when trying to shut off with the key; lever goes down to horizontal position, but the car does not shut off (I need to manually press it further down).
I guess this would confirm the actuator is bad!?
Can it be rebuilt or one needs to buy a new one?
I checked and they seem to be going for around $200, so not really cheap!

The 60x shutoff actuator should be around 30 bucks.

1987 Mercedes-Benz 300TD Base Wagon - Fuel Injection - Page 2

OK, thanks, you are right, not sure what I was looking at!
Will try replacing to see if that is the fix.

I would buy a hand vacuum pump (as suggested) and test just the stop valve. You kind of need one (plus its gage) to test the multitude of vacuum controls on any 1980's car, plus can use for brake bleeding. HF has a cheap one that works fine.