BTW... What let me back to the EGR and the associated vacuum mess atop the valve cover in the first place was a vacuum leak that manifested in the car shutting down sluggishly as well as poor shift quality. Once I eliminated that leg from the vacuum system and the inherent leak, my vacuum is back up, the IP shutoff valve shuts off the car as it should, and the transmission vacuum modulator is allowing the tranny to shift normally again.

This, however, admittedly all occurred long after I had already needlessly spent $35 for a new 3/2 valve vacuum switch (and was getting ready to spend another $35 to replace the other one) as well as $26 for a thermo-vacuum valve... Oh well, live & learn...

Here's the thread:
Vacuum Pump Rebuild (?)

__________________
-Ken Harris
1984 Mercedes 300SD
2001 VW Passat 1.8T
2004 Harley Davidson FLHRSI
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Der Dieselfanatiker

Actually I am really glad you brought that up as I'm having some occasional trouble relating to my vacuum system...I attributed it to the cold weather all of a sudden here in Virginia... but shutdown has been an issue lately and I have only owned the car since early October and ALL is new to me on this, my first diesel. I've also got oil in my ignition switch which is another thing entirely but the tranny, before I cleaned the intake banjo- line to overboost- line to ALDA and adjusted out the ALDA, the trans was getting low pre-boost power from the motor and was shifting hard...ok. Now with the new life in the motor I find the trans is really sloppy, especially 2nd into 3rd and I don't get that. Being from a gas powered backround vacuum is/was pretty simple and I'd figure it was throttle lingeage or a bad modulator but as I learn....diesel vacuum comes from a dedicated vacuum pump, which changes things a bit at least for me. The door locks are also vacuum powered are'nt they? They work in a wierd way for sure but they do work even after the car is shut down for a while...which is really a strange thing if I'm right about that...( took me a long time to figure out how to open the trunk ) need to read some more....again ...jeez I'm saying that all the time these days! Anyway, it's sounding like eliminating the EGR and plugging it's vacuum source can't hurt and might help a bit to boot. Done deal. Is there an easy way to check if the vacuum pump is working properly??...I know a vacuum gauge would be a good start but have not had the time yet and there are other priorities b4 I get there...I still need to replace the trans fluid and filter, rear gear lube, motor mounts but NOT the trans mount as the driveshaft has a weak U joint and I don't want to start wearing it in a new place...Garsh!! What else?? the list goes on but I gotta say, I've got $920 in this car so far, it has never been messed with as far as I can see, it runs pretty strong, purrs down the road and is a real treat to wrench on...and where was I?? Oh yeah vacuum. Man, I have like 5,000 questions, I'm just glad there is stuff here to read and learn and people who like to answer the dumbest stuff...so where is that EGR anyway...no don't tell me, I'm keen to guess.

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1983 300SD... 269,000 miles, nearly 2,500 on my B-100, Faded Grey, Ugly in an elegant sort of way...Duh-Benz


If any of this has been a blasphemy to you, then good, because it's been a blast for me to...A.Whitney Brown

I had the same problem. Barring anything wrong with the vacuum shutoff valve on the IP, you're likely to find a vacuum leak to be the cause of your troubles there, or I suppose a weak pump...read on...

I read recently in another thread where MB should've issued a Mity-Vac along with the first aid kit, which I think is not far from the truth... For starters, check here for a good vacuum check-up procedure and go from there...

If you've got oil in your ignition switch, you've likely got oil in your vacuum lines, since it is vacuum control of the IP shutoff valve by way of the ignition switch that shuts the engine down. It is not "another thing entirely", but likely symptomatic of the SAME problem.

When vacuum was once again tight, I found my transmission shifting a little soft for me as well where it had been shifting hard before, having been hindered by a vacuum leak that resulted in a non-functioning vacuum modulator. I had to adjust the modulator slightly as well as the throttle pressure cable (aka bowden cable) to get the shift quality and timing (respectively) as I like it. You may have the slide type throttle pressure adjustment on an '83...I'm not sure. In any event, adjustments for shift timng & quality are VERY easy to do...check here for instructions.

Anyway, have fun. Be sure and let us know when you find that EGR...

__________________
-Ken Harris
1984 Mercedes 300SD
2001 VW Passat 1.8T
2004 Harley Davidson FLHRSI
-----------------------------
Der Dieselfanatiker