My car is a 1990 2.5 diesel which recently stopped shutting off when the ignition key was shut off. Per conversations on this site, I attached a mityvac to the shutoff activator and the engine shut off immediately.

The vacuum line coming from the actuator is 4mm brown w/blue which goes into the dash area and turns toward the center, behind A/C equipment. This line has no vacuum when the key is shut off, as measured at the actuator.
This line, per my manual, should go to the ignition key but if it does so it is indirect.
The lines attached to the key are black w/grn and black and are quite a bit larger and tight. Although I have removed the cover under the instrument panel (68-150) I can't visually see where this stuff is going as of now. Would appreciate your thoughts.

Here is the way my SD works; yours is probably the same. There are two plastic lines hooked to your ignition switch. One goes to the vac pump system and the other goes to the shutoff valve which is in the rear of the injection pump. See arrow in pic below. When you turn the engine off the line going to the shutoff valve gets vac which pulls a lever inside the shutoff valve - and the engine dies. When the engine is running that line has no vac.

It sounds like the Mityvac says your shutoff valve is good so you should attach it to the plastic line at the ignition switch. If you cannot pull a vac then that plastic line is bad. But more likely the rubber connector is bad.

If you can pull a vac, then try the Mityvac on the plastic line running back to the vac pump system; you may have a leak there. And again it may be the rubber connector. The plastic lines are pretty durable.

It is very rare that the ignition switch itself is the problem but it does happen. That should be your last suspect.

Again this is from my experience with a 300SD and yours might be different. But my two cents.

http://www.peachparts.com/shopforum/attachments/diesel-discussion/79848d1271647942-79-300sd-fuel-cut-off-solenoid-picture767b.jpg

Found this from 2016

First, find the shutoff actuator and trace the vacuum line (usually brown with blue stripe) up to a point where it connects to a coupler. Plug your mityvac into it, and carefully pump it up to ~15 inches. If it does not hold vacuum or it leaks down quickly, the shutoff actuator itself is bad.

If not, the next thing up the line is the valve behind the key inside the dash. When in the on position the vacuum from the vac pump is blocked, and the shutoff actuator is vented to atmosphere. Make sure that it true. Next after that is vacuum from the vac pump. If the actuator, valve, and vacuum pump are all OK, you'll have to begin plugging and testing individual vac lines to be sure they are sealed and not cracked. Finally, if all the shutoff lines are intact, you'll have to branch off and see if there are other components that draw vacuum off the shutoff supply line (brake booster hose or the 4 way small line connector) that could possibly be leaking enough to render the shutoff inoperable. The most likely thing is that the actuator itself has a tear in the diaphragm and no longer holds vacuum.

If you have to replace the vacuum shutoff valve on the steering column be sure the two lines go back in the same positions as the came from. If the lines are not in the correct place the valve does not work as it is supposed to (at least that is what I have read on this forum).

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84 300D, 82 Volvo 244Gl Diesel

Thanks for your input; I haven't been able to get back to this for a while. I tried to get to the vac lines going to the ignition switch by removing the left lower panel but no more than a small section of the lines are visible- the black and black/green hoses attaching to the switch. When I had the entire area disassembled to replace the fan and evaporator, I checked these hoses and they were very tight so they are not likely to have come loose in a year or so, I would think. In any case, to get to these would require disassembling the instruments and maybe other parts of the dash, a very time-intensive job.

I have another issue with the vacuum system in that the rear doors do not lock and so perhaps there are other problems with the vacuum system that I should focus on before I attack the ignition switch area. Would appreciate your thoughts about that.

The shut off problem runs off the mechanical vacuum pump, maybe try putting on a length of tubing onto the stop valve. With the car running suck on the tubing it should turn off with not much problems.

The rear locks run off a separate vacuum system which is under the rear seat passengers side. Vacuum locks and pressure unlocks. The pump generates both vacuum and pressure.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Can't you just pull out the instrument cluster to get to the ignition switch? That's the way you do it on a 300SD. Easy peasy. No need to remove any of the lines on the back of the instrument cluster; it will come out enough that you can get to the ignition switch and inspect the two vac lines.

I believe in post #1 you identified that the shutoff valve is OK by testing it with vac. So again it could be the rubber connectors on either end of that plastic line or either end of the other plastic line from the other side of the ignition switch.

I believe you can search under the carpet on the front passenger side for a group of connectors going to each door. You can use a Mityvac there on a line by line basis to see which door is leaking vac. Likely an actuator problem which is an easy fix.

I have a 1986 190D and am experiencing the same problem.

I believe after a series of testing, that my problem is the vacuum connection at the ignition switch.

I can't find anything, after searching, that shows how to access the vacuum connectors to the ignition switch.

Anyone have any ideas?
What is the easiest way to access this?

Thanks!

Good job trouble shooting.

By vacuum connection are you speaking of the metal valve the hoses connect to or the tubing or hoses?

If it is the metal valve there is 2 screws that hold it to the steering column lock assembly. If there is not room to get at those you may need to find instructions on how to remove the Steering Colum Lock and unplug the Ignition Switch connector at the bottom.

Go to your favorite parts site and see if you can see a picture of the steering column lock and the valve that has 2 projecting nipples on it. That will give an idea as to what you are dealing with.

Also note the positions of the 2 tubings/hoses. They need to go back in the same nipple they came off of.
On mine it is accessed by removing the panel that is above my right knee and you can look up under there and see the steering column lock. Though people have said they managed it for me there is not enough room to get at the screws to remove the valve.

Someone else may have a free internet site where you can access the manual.

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84 300D, 82 Volvo 244Gl Diesel

I wanted to get up in there and do an inspection. I am thinking the rubber hoses are leaking. I will try removing the right panel under the dash. Hopefully that will give me enough space to get in there and look around.

Capn Jonas - what finally happened?

Yes, Capn Jonas...

And let us know how you got to the vacuum valve and hoses on the ignition switch.

I took off the bottom trim piece above the knees and also the molding behind it that goes into the foot/pedal area. I can't see how anyone could get their hand up in there let alone see the valve and vacuum lines.

I need to research further but am thinking I will have to take the gauge cluster out to get to it in my 1986 190D

CJ - here is a pic of my SD dash. Not sure if yours is the same. On the SD the gauge cluster is just friction fitted into the surrounding dash. All you do is form a strong wire hanger into an L to use as a hook. Slide it between the gauge cluster and the dash at about the 2PM point (do not quite remember) and gently pull on the cluster. It will just come out.

From there you can see the vac lines and rubber connectors attached to the ignition switch.

Maybe yours is not designed this way but thought this might be helpful. At least on the SD there is no need to remove the knee plate.

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Thank you.

Here is a pic of the back side of the instrument cluster. Not sure you can see but it is reinforced at the removal spot for the L shaped tool. You can just slide the whole thing aside without removing anything and get to the ignition switch.

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