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Vacuum-assist door closure

9K views 15 replies 8 participants last post by  Brett San Diego 
#1 ·
Hello W140 forum,

I recently became the happy owner of a 300SD (1993). I am in the process of changing all fluids and filters and generally assessing the car.
I have discovered that the vacuum-assist closure for the two front doors and the trunk does not work (the two rear doors work O.K.). Also the rear left door lock (button up/down) doesn't work. Am I looking at seperate vacuum problems(leaks?) or are several problems associated with a faulty vacuum pump?
One other problem: The steering wheel will adjust (in/out) but not tilt(up/down).
The car has 153K miles on the clock and runs fine. What preventive maintenance (e.g, timing chain) should I be considering at this point?

Thanks for this forum and all its contributors.

Rob
 
#2 ·
I have a 1993 300SD since new. The problem with your doors is most likely the pump located in trunk on left side. Usually needs replacement. The pump is behind the lining tucked in over the wheel well wrapped in foam. Hard to see. Follow the small air or vacuum lines once the trunk lining is removed. However 1st remove # 9 fuse for 10 seconds to reset the electronics. It may work for a while. The fuse is located in the trunk on the right side. The lock works off of another pump located under the rear seat onthe right side, however, more than likely if the other locks work the air line may be disconnected or the individual pod that works the lock is defective or need to be lubed. The same is possible for the doors but I think a pump replacement is in order for the doors. If the timing chain has never been changed it should be changed and if you do that a new vacuum pump on the engine may be prudent. I only have 93000 mi. on mine. Good Luck
 
#4 ·
I dont understand how can it be a bad pump if it functions with certain doors? I had a similar problem where my rear right door lost its closing assist and door lock ( two pumps loosing function). I also lost my fuel lock. This happened after i changed my right front and rear doors. I believe it was you bret that informed me of a 6mm bolt that secures the rear door wire harness and it sure was, thank you if it was you. I still havent been able to find that bolt but after removing the dust cover i heard it leaking badly right near the door hinge and missing a bolt. I cant believe the body shop missed this bolt and told me he doesnt know what the problem was. Again can it be a bad pump if it operates certain doors? I would assume a leak before a bad pump, no? I also still dont have any electrical to that door, could it be a relay somewhere or any resetting i must do considering its a new door? no window, no lighter, no side light, or should i just concentrate on this door plug?
 
#5 ·
the pump can be bad because there are individual units within the pump, so 4 can be working but 2 can be bad. take a look at the pump and you will see there are 7 or 8 hoses going into it.

Btw, be very careful in removing the hoses, the spigot head on the pump breaks off very EASILY and your pump will be useless then.
 
#9 ·
Search this forum for "closing assist pump." Lots of great info from me and others.

There is only one pump head run by one electric motor. Vacuum and pressure is fed to each line independently by solenoid switches. I've not yet heard of someone suffering a complete total failure of just one output line in an otherwise working pump. I suppose it could happen if that particular solenoid failed, but I haven't heard of it yet.

Brett
 
#10 ·
I have not seen the plug, I did see a drawing of the front one and it is oblong and all the connectors terminate there. I quote from the 92 manual " the plug connection for the rear doors is located in the B pillar. The door harnes connector can be removed by turning the square socket wit 6mm square tool (140 589 00 09 00)untill the connector is released. The opening is covered with a dust cap"
from the picture it is below and to the right of the switch in line with the top of the rubber boot.
 
#11 ·
215 Pneumatic Door Close-Very Loud Pop, now doesn't work

I heard a loud noise from what I thought was the outside of my driver's door on my 2001 CL600 last night...thought at first someone had thrown a rock at my car. Got out, looked around, didn't see any damage, but now the pneumatic door close will not work. I can close the door manually and the windows still seal. Was that loud noise an air bag or something exploding like a balloon? Passenger door still works.
 
#13 ·
I heard a loud noise from what I thought was the outside of my driver's door on my 2001 CL600 last night...thought at first someone had thrown a rock at my car. Got out, looked around, didn't see any damage, but now the pneumatic door close will not work. I can close the door manually and the windows still seal. Was that loud noise an air bag or something exploding like a balloon? Passenger door still works.
You have a W220. This is the W140 forum (1992-1999 S-class, for North America). I don't know if the fuse diagram posted by Cool applies to your car. Regardless, if you pull the fuse for the pump as Cool says (and, i think there is only one pump on the W220), it should reset the pump and ensure that your driver door's air line is working. Then if the door doesn't work, something is definitely amiss. The pop sound may have been the acuator going boom. This would cause a major air leak in the door. If the door still doesn't work after resetting the pump, you might be able to hear the hiss sound from the leak when you close the door. Listen carefully for it.

Brett
 
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