My brother just bought an 84 300D turbo. When he first picked it up, it started and ran fine, but would run for a few seconds after turning the key off before finally shutting down. By the time he got it home (from Texas to California), the car wouldn't shut down, the brakes felt hard, center vents didn't work, and neither did the door locks.

Went at it today with a mity vac, discovered some broken vacuum fittings and some mickey moused lines. Cleaned everything up, hooked it all up, and it is better, but still not right. From the main line, there are two branches off into the system. from the branch furthest forward, I pump it up and the vacuum just leaks out immediately. Each individual line holds vacuum, but when it is all together and drawing from one central spot, it all leaks out. The same is true for the branch further aft, except the leak is much slower. I pump it up, and it holds for maybe 5 seconds, then drops a half an inch, then holds again, and drops, and so on. Again the individual lines hold, but not when all put together.

Last thing I noticed was with the car running, and testing from the main line, the pump puts out a steady 20-25" hg, but testing somewhere else in the system, it doesn't go higher than 10, and got there very very slowly.

As it sits right now, the car will shut off with key in about 5 sec or so after turning the key to off, and the door locks will work, slowly, when it is running, and maybe once, slowly, after it's shut down. Any ideas? Thanks!

It's been my experience that leaks can occur at the joint between the rubber and plastic lines. I would replace the rubber joint sections where you can.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

It doesn't shut off because of a leak. The other symptoms are from leaks as well. Now the question is where?


There is a main line goes from the vacuum pump to the power steering booster. Because you said the brakes at one time were hard, I would cap off the 2 feed points and see if the brakes operate properly. If the work you already did has restored the brakes, skip this.

Uncap one of the feed lines and check vacuum and then shut off the engine and watch it. It should hold for a period of time.

The other vacuum circuits supply vacuum to climate control, door locks and engine controls.

By connecting a MityVac to the two lines fed vacuum off of the main, and creating vacuum, you can see if they hold.

If one or both leak, you need to go down to the first split and check each of those plastic lines and continue to do so until you find the system (Climate control, locks, engine controls) that has the leak.

Once you found the system with the leak, you need to find the source of the leak, within that system by checking each line and the unit that is using vacuum.

Stay patient and take breaks. It can take time.

Don

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1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it

He obviously meant to say "power brakes", but the rest of the advice is good. I recently found two small leaks in the vacuum system on one of my '82 300Ds. I isolated various parts of the system, checking each with the Mityvac and eventually found all the leaks. Those 3-way and 4-way rubber connectors are cheap. I'd replace them all on general principle.

Good luck,
Wes

Someone here posted awhile back how to troubleshoot the vacuum system with little ease. I followed his guidelines about a month ago on my wifes car and found the problem within an hour. I had similar problems with hers. It all started when the car took it's own sweet time shutting off. Then the locks stopped working and eventually it wouldn't turn off at all without hitting the master kill lever under the hood. My problem turned out to be two vacuum diaphragms in the back two doors. Pulled the replacements out of my car, put them in hers and her car now runs like a champ. Now, my car won't shut off when I turn the key, so I have to leave it in gear, hold the brake pedal down and let out the clutch...kills it each and every time. One day I'll get around to ordering the parts for mine.

Mike

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Mike

'80 300D
'84 300D
'85 300D
'87 300D

Got the leaks! One was the grommet where the vacuum line went into the resevoir in the trunk, wrapped some electrical tape around the line, slowed the leak WAY down, to a point where I'm satisfied. The other one is in the shut off line from the firwall to the shut off valve. It is either the connection to the valve, or the valve itself, any ways I can rule out one so I know it's the other? Thanks!