Thanks, Griesel. Good to know I'm not the only one who can't figure out the vacuum system.

Here's what I did today: I suspected that the two-prong vacuum valve on the ignition assembly was the culprit, so I took it off to inspect it. I figured out that the ignition assembly pressed the button in when the key is in the turn-off position. When the button is pressed in, I can blow through one nozzle and out the other--is this correct? Shouldn't one nozzle be closed at that point? I'm really not sure how this little gizmo is supposed to operate. The car runs with either line is not allowed to reach its connection point under the hood--but, when a vacuum "circuit" is made, vacuum just shoots straight through the ignition valve and shuts off the engine .

So, is it the valve on the ignition that's bad? Could it possibly be that the valve is fine and the ignition assembly is not engaging it correctly? Could it be something entirely different causing the problem?

I put the brown/blue line on the nozzle closest to the main body of the ignition assembly, and the plain brown one on the outer one. The brown/blue one runs to the shutoff valve at the injector pump and the brown one feeds into a three-way rubber connector--I could feel vacuum at this connector.

Am I making any sense?

I'm getting discouraged.

Does the above info ring any bells for anyone?

But, at least my car runs and has a/c. I just left the line running into the injector pump valve and removed the line from the three-way connector (I plugged this line and the three-way connector branch with screws). I just have to shut the car off manually now.

This can't be as hard as I'm making it.

I've narrowed down the problem. So, I thought I'd start a new one with a nifty diagram attached that I made in some new cutting-edge program called "Paint."

So, here's the deal: My shutoff valve on the injector pump works fine. Either the part of the ignition assembly that engages the ignition shutoff valve is faulty or the ignition shutoff valve itself is bad. The shutoff valve is pictured in my diagram in with the ignition in the engine running and engine off positions. This is is a small piece--about an inch-and-a-half long, that attaches to the side of the ignition assembly with the button going into a hole in the assembly. It has two vacuum lines attached to the smokestack-looking things (is that the technical term?)--one that gets vacuum and one going to the other shutoff valve in the engine compartment.

I've attached a diagram that shows how the valve is operating--it seems to me like it's not working correctly, but I'm not sure. There are 3 openings (blue on the diagram). When the ignition is turned to the running position (ON), the button on the end of the valve (black arrow) is not pressed in by the mechanism in the ignition housing, valve "3" is closed, and valves 1 and 2 are open--this allows vacuum to enter through valve 2 and continue through valve 1 to shut off the engine via the injection pump shutoff. I can reverse the vacuum lines and it will operate the same way--this does not make sense because dieselgiant says that the shutoff will not function correctly if the two vacuum lines are mixed up--in my case, it makes no difference.

When the ignition is turned OFF, the button is pressed in by the ignition mechanism and the vacuum coming in through valve "2" is cut off, allowing the engine to run.

I don't know what function valve "3" has.

Can anyone tell me if this valve is functioning correctly? I hope it's not--it's $25 to replace and a new ignition housing is quite a bit more. Right now I've got the valve dangling under the dash with a rubber band wrapped around it and pressing a piece of wood into the valve button.

Jeez...sorry that was so long-winded.

Thanks in advance...Attachment 42924

Ummm...let me try that attachment again...Attachment 42925

No one knows anything about this?

I think I just read in another thread that it must have a vacuum on that line to the IP when in the off position and thats what shuts it off... Someone said put the line in your mouth when car is running and suck it real good to test if you don't have a mityvac...


...i have the "no turn offs" too right now....

lemur, did you ever solve this problem?

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Well, that depends on what you mean by "solve." I just left the valve hanging off the ignition by the two vacuum lines and rigged the clicker from a ball point pen to the valve button with some epoxy. Now I just push the clicker when I want to start the car, and push it again to stop it (better than the slab of wood held by a rubber band that I had before). I tell myself that it's an ingenious anti-theft device.

I got another valve at the junkyard (practically for free), and it works the same way as the original. So, I guess it's not the valve. It's probably that the ignition assembly doesn't operate the valve correctly, i.e. keep the button pressed when running. I guess I need to start saving for a new ignition assembly.

Well, how this is supposed to work is that a circuit is made when the ignition is turned OFF. When on, there should be no connection.

I haven't ever had to take my assembly out and look at it, but it looks like on your diagram, the line from the vacuum pump should connect to three and the line to the shutoff pod should be on one.

Try that, it should work unless there is something else messed up.


The one thing, everything that I have seen indicates that the lines should be on one and two, but something is screwy here and that doesn't work. Who knows, I might be wrong, but try this and see it it works.

__________________
1984 300DT turbo 138k mi

Still hauling me to school and back.

Handy Site:
http://www.dieselgiant.com/

Yeah, vacuum runs to the ip shutoff valve from, or through, the ignition shutoff valve. My problem is that when attached to the ignition assembly, the ignition shutoff valve allows vacuum to the ip shutoff when the key is in the "car-should-be-running" position. So, I had to rig it so that I, not the ignition assembly, can operate the valve. Am I even making sense?

rbardolv, what are your "no turn off" woes? Is your ip shutoff not working?

Arew264, that makes sense, but the problem is that number 3 fits into a hole in the ignition assembly, so I can't attach anything to it. Here's a pic of the part--the number 3 opening is facing you (holes around the "button") itAttachment 44135

Well, 1 and 2 are definitely where the lines are supposed to go, but it seems like your ignition is opposite how it should be. My guess would be the tumbler (not this switch). It should be pushing that button when you turn it to the on position to cut off the circuit.

It could be the other way around, but it would appear to me as it it's more likely that the vacuum switch is correct because if it was made wrong, it wouldn't hold vacuum with the button pushed in (if you connect a mityvac to opening one when the button is pushed, you get no vacuum right?).

This is just really weird, and I would tend to think that the new tumbler somehow went in wrong... or it could just be screwy.
My advice would be to check it again even if you're sure, because I've been sure of a number of things like this and checked again... and suddenly found I shouldn't have been.

HOWEVER: you are definitely correct in that this is mechanical - nothing electrical involved.

__________________
1984 300DT turbo 138k mi

Still hauling me to school and back.

Handy Site:
http://www.dieselgiant.com/

Yep, it's weird. I'm wondering if I put the cylinder in incorrectly, but I do seem to recall that it would only go in one way. I think I'm just going to have to pull the whole assembly out (ugh) and get a good look at everything. I'll post the solution to this problem once I figure out what it is. Why do I get the feeling that the problem is a really basic fix and caused by something really stupid that I did? Time will tell...

Seems I read another recent thread on this same topic. I didn't commit much to memory (because I don't have this problem right now), but from what I understand, there is a specific position for the switch to be in before reassembly? (needs to be in position 1)

__________________
1982 300CD Petrol/Black Leather

I finally fixed my ignition! I removed the whole assembly. Then, I removed the ignition switch from the assembly. Once I did this, it was easy to see there was a problem--there was an aqua-colored plastic disk with a raised portion on one edge under the switch. The raised portion was supposed to keep the valve button pressed in when the key was turned to the last position. It was backwards. I just fooled around with it until it functioned correctly. Man, I'm glad that's fixed.