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rodsob 10-28-2003 08:30 AM

new shutoff valve problem..pls help
last night i installed a new shutoff valve on the side of the IP. I'm pretty sure i did it right. the car still won't shut off sometimes. what did i miss? are there any other areas i should look into? help!

Rick Miley 10-28-2003 11:08 AM

The problem might not be the shutoff valve. Connect your MityVac directly to the vacuum line to the shutoff valve and see if it stops the engine. If so, then your problem is elsewhere. Most likely it is something in the door locks or the climate control The MityVac will help you track it down.

luckys420 10-28-2003 12:33 PM

I had a similar problem, however the problem was in the ignition switch itself. the vacuum swith was full of gunk, i cleaned it out with brake cleaner and blew out the brake cleaner with compresses air and it works puuurrrfect.
it doesnt hurt to check it out

sixto 10-28-2003 10:04 PM

Did you hook the shut off valve to the lever in the IP? If not, it's not doing anything.

95 S420
91 300SE
87 300SDL
83 300SD

84300DT 10-29-2003 08:04 AM

my latest method for cleaning/clearing the vac lines going through the key switch. disconnect the two vac lines - one going to the shutoff valve (brown) and the other from the vac source (green).
take volleyball hand pump with needle-
place needle into green line - pump like hell til oil stops coming out of brown line. you're done! least til it clogs up again which for me varies 2-4 weeks.

Rick Miley 10-29-2003 09:41 AM

84300DT - your shutoff valve on the back of the injection pump is leaking. That's where the oil is coming from. You should go ahead and replace it before the oil eats up the rubber parts in the key switch and then you have two jobs to do.

84300DT 10-29-2003 10:06 AM

rick, yes, thank-you , i know .. i have replaced the rubber connectors at the key switch (along with a lot of ###%%%:p )
the shutoff valve replacment is skeering me a bit though i must admit. any precautions one can take when doing this? ie, in case the engine runs away?

Rick Miley 10-29-2003 10:11 AM

Have the correct size open end wrench in your hand ready to loosen the injector lines when you first start it up. Have a helper start it so you can be "at the ready."

Admiral Ahani 10-29-2003 10:22 AM

HELP! I need somebody...
I have a problem shutting off my car too. About a month ago I changed the hydraulic accumulators (air cells) on my '82 300TD T and the ride has become much much better! But, on the other hand, ever since doing that repair, my locks have stopped working right (the locks don't budge when the car is cold and it looks like they are trying to open when it's warm, but they never open). Additionaly, the engine won't shut off and I keep using that manual shutoff lever which is embarassing and a hassle.

The locks and shutoff worked right before the repair, and stopped working right after. Either it's a freaky coincidence, or I messed something up. I worked carefully, but one bad thing I did was to clamp the strut hoses to keep them from pouring fluid on my face - my dad later told me that was really bad, but I don't think that could have broken the vacuum system. Maybe I broke the vacuum reservoir as it is right there next to the accumulators... Also, I flushed the hydraulic fluid AFTER the vacuum problem came up. Thanks in advance for all your help!


84300DT 10-29-2003 10:28 AM


Originally posted by Rick Miley
Have the correct size open end wrench in your hand ready to loosen the injector lines when you first start it up. Have a helper start it so you can be "at the ready."
thanks for the tip- however,
isn't there a way to ''test'' the new valve before starting the engine. i seem to remember somebody saying that ?

rodsob 10-29-2003 10:29 AM

when i removed the old shutoff valve, a little oil oozed out of the IP where the shutoff valve sits. is that normal? maybe that is my problem? help!

Rick Miley 10-29-2003 10:44 AM

Boy, this thread is turning into a real mess.

All three of you need to get a MityVac ($26 at AutoZone) and use the search feature here because all these things have been discussed many times before.

Admiral - a hand operated pump with a gauge (such as a MityVac) is absolutely essential in diagnosing the problem.

84 - the test posted was to apply vacuum to the shutoff valve and see if it moves the stop lever. However, that test is not valid for all injection pumps.

rodsob - no that's not your problem. Did you do the test I posted.

[Rant]All of you - get a MityVac before you do ANYTHING else![/Rant]

84300DT 10-29-2003 10:54 AM

what is this mityvac you are talking about..??? :confused:

j/k rick ;) ;)

autozen 10-29-2003 11:02 AM


There is absolutely no connection to the hydraulic rear suspension and the vacuum system. The failure is either a coincidence or you did break a fitting on the resoirvoir.

84 300DT,
If you install that suut off incorrectly you do run the risk of the engine running away, and I don't think you will get the injectors all cracked in time. I dought if anyone here can attest to the fact that it worked for them. The only sure way is to remove all the air cleaner stuff and be ready to slap a 2x4 on the hole. While removing the old unit, pull it straight out gently after you have removed the 4 screws. You will feel it tugging on something like a fish hook caught on a snag. What you feel is the rod of the unit hooked into a hole in the main rack. Just before you start rthis process, take a look at the new unit, and you will get an idea of what is going on. Now tilt the old unit to the side to unhook and pull straight out. Now that you see how it all works, stick the new one in the hole and hook the hook. You can test by tring to pull straight out like before. If you feel the tug, you're hooked. Push it straight back into place and hold it in position while you screw the holding plate back down. If you don't hook the hook, the unit pushes the main rack to full fuel, and there is no shutting it off. Remember a diesel needs to compress air into a tiny space for the injected fuel to burn. If you dlap a board across the air intake, you get injected fuel in the cylinder but no air to cause combustion.

Good luck,

Admiral Ahani 10-31-2003 11:08 AM

I will buy a mityvac this afternoon (assuming kragen has it). I heard that troubleshooting the vacuum system is a little burdensome since you have to take all the doors apart and other stuff - is there a typical failure that occurs in this system that I can check for before opening everything up?
And if I did indeed loosen a connection to the reservoir, how would I get access to these connections (I didn't see them from underneath the car, are they on top?). Thanks for you help!


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