If your vacuum pump is bad your engine will not shut off using the key, your power brakes won't work, door locks won't work properly, the trans will shift pretty hard, and usually there will be quite a bit of oil in your air cleaner housing (and subsequently on the ground beneath the passenger side of your car.)

I would suggest looking in your air cleaner housing. if there's a lot of oil it's there because the diaphram in the vacuum pump is torn, causing oil from the crankcase to be forced through the positive pressure dicharge line that discharges through the lid of the air filter housing.

rebuild kits are available for about $20-35 dollars. i recently rebuilt mine, and within 2 weeks it failed again. It is very possible that it failed because I didn't install it properly. I've ordered a new kit, and will see if I can find torque specs for all of the bolts. If it works I'll let you know.

Hello Biodiesel614...I am looking at my Vac pump here on the desk..I do not know which way the large diaphram goes in...saw your post on the failure and wondered if any luck on diaphram orientation ??...I cannot find any tech info on this thing...fits a 1980 240D.....

the following link:
http://www.peachparts.com/shopforum/search.php?searchid=726081
"YELLIT",
This was the result of going to the opening page for the "Diesel Discussion" forum, doing a SEARCH within this forum and using "Rebuild Vacuum" as my search words... specifying the search to be in the title lines only!
Sam

Look, there is a simple place to always start, and this is assuming that you don't have a Mityvac YET (you will need one).
We'll assume you have brakes, as usually folks do.
*First, find the main vac line from pump to brake booster.
*you vac line may have one or two "T"'s coming off of it
*from one of those, find the lines that go back to firewall just next to brake booster
*Green is to climate, Yellow is to door locks, yellow w/ gray stripe to vac reservoir, brown to ignition shutoff, and black just vents under dash.
*Unplug green and both yellow lines and plug the connector they came from. The lines going into the firewall can just sit there.
*Now start the car and let it run for a couple of minutes, then try and shut it off. If it shuts off, then you have a leak either in the climate control vac lines, or the door lock vac lines. Attach one at a time, let motor run and shutoff again. You can find the offending system that way.

if you still don't shut off, report back. Then it could be vac pump, shutoff valve, ignition switch piece, loose brown line to ign, or from ignition to shutoff on back of IP, to name a few.

Also, if you have a second "T" off the vac line, you may have to plug that one also for this test.

Report back......

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

There is no Vacuume mod on the 78 Trans..... It's all TV Rod and electric