I know it’s summer but I have time now to work on it. Not so much in the winter. Last winter as the temp would drop down below say low 30s our 240d would only shut off with the emergency shut off under the hood. I checked for vacuum leaks (couldn’t find any) & vacuum (about 25hg). I also replaced most of the rubber vac. fittings last fall. When the temp would get warmer it would have no problem shutting off. What is the possibility the fuel shutoff valve is the problem.

Hard to isolate the problem when not present.

Could even be the rear portion of the ignition switch. That turns the vacuum on and off for the fuel cut off device. You may have to wait for it to get colder to diagnose it.

Try adding a drop of two stroke next winter, maybe the winter fuel blend is not so lubricity (almost, but not quite a made up word).

__________________
David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

I have similar issue. In cold it will almost shut off but continues to stumble. Sometimes shaking the key briskly in the ignition will get it to shut off. I suspect its the vacume switch on the ignition lock assy, perhaps some old oil/grease that thickens in cold and wont allow the switch to slide completely.

I'll call BS on the diagnosis statements. A $15 part isnt worth waiting 6 months and multiple days to diagnose before replacing. Just do it.

This makes it sound like the Vacuum Shutoff Valve that is on the Steering Wheel Lock Housing. When it is cold out the worn seal inside could be shrinking enough to allow for a vacuum leak.

Has anyone connected a Vacuum Gauge between the Vacuum Shutoff on the Fuel Injection Pump and the Vacuum Line that goes to it and see how much Vacuum is available when it is cold compared to when it is hot?

Inside of the Steering Colum Lock the Vacuum Shutoff there is actuated by a Plastic Cam. I suppose that if that was worn enough and contracted from the cold weather it could also cause the same issue.

Attached Thumbnails

 

__________________
84 300D, 82 Volvo 244Gl Diesel

I’ve looked but can’t find the vacuum shut off for the ignition switch on pelicans site. Anyone know where to look?

Very easy to diagnose when acting up. A vacuum gauge on the line to the ignition shut off. Making sure vacuum is present at the time in the main system. Should take less than five minutes.


For the poster than has to shake his key it is the obvious problem. Change the ignition shut off on the back of the tumbler. No diagnosis required.


Although I would have a peek that the vacuum hose is still in decent shape. It might be leaky itself. This is unlikely though with his description. Yet not in the case of the first poster. All the components are really old by conventional car standards.


The other poster has no assurance of what one of the three probable possibilities are. For example the internal diaphragm in the shut off itself could be leaky in the cold. There is no way to be sure of what it is until he has the problem again. Once again though as the injection pump is usually at least warm in the winter when he tries to shut down. The shut off on the pump is probably also up to temperature. This makes it a weaker suspect in his problem.

If I'm not mistaken, the vacuum switch and ignition lock are one unit. Fortunately, they have come down in price but still cost enough that you would want to ensure that is the problem. Not to mention how difficult the replacement.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

On my 83 300D it is a separate part. About as tall as a quarter and held on to the lock cylinder by two screws. Did a google search for “w123 vacuum cutoff” and the top result I saw was one for $25.

Before buying the part though I’d say get into the switch and make sure that the short rubber line sections connecting the hard tubes to the switch aren’t leaking in cold weather. That seems like a more likely culprit for a leak to me. But while you’re in there it would definitely be a good idea to clean and lubricate any part of the mechanism you can before it breaks like mine did.

__________________
'83 300D turbo diesel (334k daily commuter)
SOLD '80 240D 4 speed manual, #2 piston pitted from crushing a 10mm nut. Running it 'till it burns through.
'78 F-150 300cid 4spd od (with my great unkle's original sales receipt)
SOLD '66 Ford P-350 delivery truck (almost driveable)
'49 Dodge B1D (1 ton Pilothouse era truck) not running but all there, candidate for om617 and 4x4 conversion when money permits.

Here is a picture. This is the part number that is in my notes but anyone should double check.
0004600284 shutoff valve on steering Colum

Attached Thumbnails

 

__________________
84 300D, 82 Volvo 244Gl Diesel

You need a hand vacuum pump w/ gage to diagnose any vacuum problems in your car. HF has an affordable one in the "brake bleed kit" or pay more for Mighty-Mite brand. Just connect the pump to the shutdown valve's nylon hose, hand-pump and see if that shuts off the engine and holds vacuum.

Best to install a small, clear filter in that line. When you see oil in it, you know the shutdown valve diaphragm has ripped and lets you correct that before you get oil all thru your vacuum system.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans