My 92 300D is starting to get sluggish when turning it off. It is starting to run on a couple of seconds. Anyone have an idea? Does this car shut down with vacumn or fuel solenoid? The car just had a new vacumn pump installed in January. TIA, Ernie

Could be the vacuum stop valve starting to go or a bad vacuum signal to the stop valve. That includes a bad vacuum valve at the key switch (what do you call the un-ignition switch?).

Look for the ~30cm diameter thingy sitting on the IP ahead of the ALDA. There'll be a vacuum line leading to it. Two screws hold it down. I'm not sure if it can be replaced without taking off the intake manifold on a 602t.

Essentially it pulls on the same lever as the manual stop lever on the IP.

Sixto
91 300SE
87 300SDL
83 300SD

The vacuum "power " number is as, I recall from another thread is 18 to 21 inches of mercury.

A good vacuum gage is vital.

But you can also do this : if the '92 has the same system as a W123, 1980 300d, then connect a plastic hose to the solenoid, with the engine running and with human power try to "kill" the engine.
This is what I had to do when my old system had too many leaks, it worked well, about 2 or 3 strong inhales would activate the fuel shut off.
The "kill" times should be about the same, manpower vs vacuum pump power. If not, then, most likely there is a leak somewhere. Of course, if the shut-down time is still slow, then the solenoid may be worn out.

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Adrian
'80 Mercedes 300D ..sold..
two Diesel VW caddies, old ones ..sold..
'96 Saab 900S

When you shut the car off, the lever on the injection pump that has the red sticker that says STOP, should go down right away and stay down. If it is back in the up position then your vacuum shut off valve is the problem.

You can replace the valve (I think it is around $20$30 for the 602.962 motor) without removing the intake. You will need a 1/2 drive ratchet, a universal a 2 4 inch extentions.

When replacing the valve & gasket, please check it BEFORE you start the engine to make sure it catches the internal latch OR ELSE!!!!!!!!!!!

I do not want to scare you, but if it does not catch, the engine will go to full load and you will not be able to shut it off aside from cracking open some fuel lines which will get very messy in a matter of seconds. Do not ask how I know this

CJ,

Another emergency shut off is to plug the engine air inlet. Isn't messy either.

P E H

When blocking the air inlet, use something stiff like a mousepad or flipflop slipper, not a rag or something that the turbo can ingest. I don't know how fast it's spinning on an unloaded runaway, but that's not the way to find out.

Sixto
91 300SE
87 300SDL
83 300SD

The MB fuel shutoff is vacuum actuated (the Cummins is an electric fuel solenoid). There is a metal/plastic can on the top of the pump with a vacuum line running back towards the brake booster and into the dash. Another line from the dash comes back out around the strut tower to the brake booster line. This is the vacuum shutoff circuit. Likely points of failure are the shutoff switch on the pump or the vacuum unit behind the keyswitch or both. But the caution about the runaway diesel is true. Be sure to vacuum test the shutoff with the engine off. The stop lever should move up and down. I've done this on my 1987 300D.

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Brian Toscano

I picked up the vacumn switch today for the 92. Boy, Its near impossible to get the vacumn switch off. Any suggestions? This is a 92 and has a little bit different set-up. The aneroid valve is blocking access to the vacumn switch. TIA Ernie

On my SDL I couldn't get the inner bolt back in wihtout removing the ALDA.

Maybe if you shave a 10mm box wrench you can do it.

Sixto
91 300SE
87 300SDL
83 300SD

Sometimes these things can be a *****, sometimes the "shortcut" takes more time than simply removing items, even the manifold. Yes, I still have some "shaved" tools. Also slotting a hex screw can be helpful. Little bungie cords come in really handy..
I can remember on an old Saab 99, there was one screw on the powerpack to R and R, I could never see it, could only feel it.

But my '80 300D is quite EZ to repair and service.

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Adrian
'80 Mercedes 300D ..sold..
two Diesel VW caddies, old ones ..sold..
'96 Saab 900S

Don't let Larry Bible hear you say that

Sixto
91 300SE
87 300SDL
83 300SD

Yes, in comparsion to the '88 Accord with 38 plus vacuum lines, and things packed in so damn tight that they cannot be found ! The bigger the vehicle, the better, usually.
But, your reply was funny, sixto.

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Adrian
'80 Mercedes 300D ..sold..
two Diesel VW caddies, old ones ..sold..
'96 Saab 900S

The ALDA is held down by a captive nut. Just take two medium Crescent wrenches and use one to hold the ALDA and the other to unscrew the nut -- once it's loose you can remove it by hand. Easier and faster than removing the manifold.

I did this to change mine, same problem. Slow shuttoff going to no shutoff.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!