vacuum reservoir conections - PeachParts Mercedes-Benz Forum

JHZR2 · #1 05-06-2003, 11:33 AM

Hi all,

My car's vacuum has been getting progressively worse over the past months. It got really bad during the cold spell this winter, and I just have to do something.
I realized that one of the two nipples on the line that goes from the vacuum pump to the brake booster had broken off. Apparently the broken one was sealed, Id never hear noise from it or anything, but I got a new one of those and made the vacuum lines back to how they are supposed to be according to the performance products catalog.
I thought it was better, it always shuts off now, doors usually work when the car is on, the midle air vents open occasionally rather than never, etc., but the problem is now only this:
-when I turn off the car and leave it unlocked for more than a minute or two, I loose all locking vacuum and have to lock the doors manually.
-when I lock the car immediately, and then go to unlock it more than a day or two later,it wont unlock all the doors.

Any suggestions what this could be? Everything else is tight.
Do the vacuum reservoirs for locking go bad/crack? Is there a check valve on there that might be bad?
I would just assume find a spot and start replacing vacuum connections. I figure its good practice for the vacuum system, since the connections are all 20+ years old. Is there one central location where vacuum is transfered from the reservoir in the trunk to the six locking locations? a manifold of sorts? If I can find this and replace all those local vacuum conections, its a start thats cheap, easy, and will make me happy that I dont have 20 year old rubber in there (even if it does still hold vacuum)
Thanks very much,

JMH

MikeTangas · #2 05-06-2003, 01:22 PM

Chances are the vacuum resevoir is fine, probably the resevoir connections too. More than likely you need to spend a bit of time and replace every rubber vacuum connection you can. The rubber at these connections gets hard or cracks and leaks so once you shut down the vacuum bleeds down rapidly.

If the vacuum still bleeds down after replacing all the connections you will have toi start the hunt for a leaking diaphram elsewhere in the system. It's doable, just time consuming.

JHZR2 · #3 05-06-2003, 02:06 PM

Can you enlighten me as to how to access the main connection point where the vaccum goes to the various doors? If I recall correctly, there is a location, maybe in the driver's door, thathas a manifold of sorts that takes the vac inpt and spreads it to the various doors... Thats my first target.
Thanks!

JMH

#4 05-06-2003, 02:33 PM

You will need to pull the door panel off (it lifts up over some plastic hooks on the panel, after removing all the screws) and the lock sends vacuum on to the door locks.
That is not usually the problem. Most often it is the vacuum push/pull units on the other doors. There is black rubber membrane that holds the vacuum and either pulls the locks down, of pulls them up. That membrane rots out.
You will very likely find at least one of those in the other doors that has a hole somewhere. Just take them off and put some vacuum on either line. If it doesn't hold then replace it. Some use latex rubber gloves and make new membranes for them.
While you have the doors apart check the vacuum lines to see if they hold vacuum. That can be deceptive though if one of the door lockers is leaking it will make the whole system lose vacuum.

RAYMOND485 · #5 02-28-2006, 07:24 AM

1984 300d Turbo 137k
Check The Fuel Door Lock Remove Side Panel Apply Vac, And May Be The Trunk Lock 4 In 4x4 Panel Near Trunk Lock, I Replace All
Vacuum Locks, The Fuel Door Is Spring Normal Open, Lock All And Push On Fuel Door After 8 Hrs If Is Unlock Overnight Replace

Diesel Giant · #6 02-28-2006, 04:58 PM

Maybe this can help you track it down.

http://dieselgiant.com/mercedesvacuumtroubleshooting.htm

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