Vacum pump
Thread Starter
Newbie
Joined: Aug 2006
Posts: 4
Likes: 0
From: Brantford On, Canada
94 S320 W140 sedan
Vacum pump
My vacum closing assist pump (located in trunk) gave up. Upon inspection this is what I found 
... pic... Does anyone Know of a repair depot or where a replacement part can be purchased......dealer only wants to sell new pump assembly. Seems a waist to have to throw the whole pump away for such a small part. 94 S320 W140 sedan just clicked 290,000kms
Zibby
... pic... Does anyone Know of a repair depot or where a replacement part can be purchased......dealer only wants to sell new pump assembly. Seems a waist to have to throw the whole pump away for such a small part. 94 S320 W140 sedan just clicked 290,000kms 
Zibby
Senior Member
Joined: Jul 2003
Posts: 455
Likes: 1
From: Fl
92 500sel/01 320e wag
Close assist
As most can remember one of my major issues with my 92 500 SEL, is the vibration issue, and close assist pump issues. I have given up on trying to eliminate the vib issue, and have it down to minimal. I have gone the Bose and AC evaporator route, but every five years or so the closing assist pump goes.
In 96 or so they replaced it, and then also replaced the trunk latch since there was a service bulletin. The latch was replaced after the pump since the trunk acted up at N/C.
In late 01 the doors and trunk started again, MB replaced the pump (we had an agreement that I would pay if there was something defective). Well they lost, and it was a N/C, since they found nothing wrong (customer adjust).
Recently the trunk lid is not always pulling down (if you do the fuse thing it will work for weeks or days).
I hate to take the pump apart, I hate paying the $600, and am almost back to putting in a relay that breaks the cicuit to the fuse whenever the trunk light comes on, or a mercury switch when the lid opens. I will have to work on the logic a little, or just a push button so I dont have to open the door to remove the fuse and re insert.
No issues with the doors, maybe I will soak down the lock with cleaner.
A new pump always seems to correct it "for a while", its all those damm safeties...I threw away the last pump after three years, I probably should have done a "post mortem" to see what is in it. I pretty well understand the system, I have the DVD, have an electronics background, and have worked as a mechanic.
As to rebuilding one, there have to be take outs at MB dealers, I know there were rebuilders paying mechanics $50 for cores
In 96 or so they replaced it, and then also replaced the trunk latch since there was a service bulletin. The latch was replaced after the pump since the trunk acted up at N/C.
In late 01 the doors and trunk started again, MB replaced the pump (we had an agreement that I would pay if there was something defective). Well they lost, and it was a N/C, since they found nothing wrong (customer adjust).
Recently the trunk lid is not always pulling down (if you do the fuse thing it will work for weeks or days).
I hate to take the pump apart, I hate paying the $600, and am almost back to putting in a relay that breaks the cicuit to the fuse whenever the trunk light comes on, or a mercury switch when the lid opens. I will have to work on the logic a little, or just a push button so I dont have to open the door to remove the fuse and re insert.
No issues with the doors, maybe I will soak down the lock with cleaner.
A new pump always seems to correct it "for a while", its all those damm safeties...I threw away the last pump after three years, I probably should have done a "post mortem" to see what is in it. I pretty well understand the system, I have the DVD, have an electronics background, and have worked as a mechanic.
As to rebuilding one, there have to be take outs at MB dealers, I know there were rebuilders paying mechanics $50 for cores
Last edited by Peter Guenther; Aug 23, 2006 at 05:30 PM.
Newbie
Joined: Jul 2006
Posts: 14
Likes: 0
From: Bristol UK
300SEL (S320)
Don't think you'll find one of them anywhere BUT you may place a request for a faulty unit and recover the part ?? or as the previous poster listed get one fabrcated, may not be that expensive... maybe a friendly model maker type person may be able to knock one up in an alloy material failing that try the arodite route what have you got to lose.
best of luck
best of luck
Newbie
Joined: Aug 2013
Posts: 4
Likes: 0
500 s
Is there anyone who can simply describe where the pump is located that regulates the doors and trunk soft assist.
Ihave spent hours reading but no real answer as to where in the s5oo trunk this pump is located. if you have a picture
a picture is worth a thousand words. One simple diagram would make it so easy for a novice to follow. Help
Ihave spent hours reading but no real answer as to where in the s5oo trunk this pump is located. if you have a picture
a picture is worth a thousand words. One simple diagram would make it so easy for a novice to follow. Help
Last edited by alfredbutters; Aug 23, 2013 at 11:52 PM. Reason: poor typing skills
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MBWorld Fanatic!
Joined: Jun 2010
Posts: 1,246
Likes: 52
From: tennessee
s320
alfred try the benzworld forums in the w140 section.zidbenz you can find trunk pumps in wrecked cars,I've never heard of them being replaced as they can be adjusted
Last edited by oldsinner111; Aug 24, 2013 at 04:42 AM.
