Droning (?) Noise on 1996 C220
Thread Starter
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Joined: Apr 2002
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From: NYC
red bicycle
Droning (?) Noise on 1996 C220
Hey,
I posted this before in the W202 forum...and found two other people with older Cs with the same issue. We think it might be the vacuum pump.
My 1996 C220 makes a droning noise, which seems to be coming from behind the rear passanger-side seat. It's very muffled, and is only noticable when the car is stopped. The sound is intermitten, and is consistent in length (about a second long). Unfortunately, that's the best I can describe it. It's not annoying, and the my C drives great...but I'm just curious as to what it may be.
systemguide (1995 C280) wrote:
I hear a constant pumping noise from the right back side of the car. Opened the trunk and removed the wall cover and the noise seems to be from a pump looking think with a few hoses connected to it. It sounds like a fan motor turning on and off every 5 seconds none stop.
Anyone here can help us??? Thanks!
Todd
I posted this before in the W202 forum...and found two other people with older Cs with the same issue. We think it might be the vacuum pump.
My 1996 C220 makes a droning noise, which seems to be coming from behind the rear passanger-side seat. It's very muffled, and is only noticable when the car is stopped. The sound is intermitten, and is consistent in length (about a second long). Unfortunately, that's the best I can describe it. It's not annoying, and the my C drives great...but I'm just curious as to what it may be.
systemguide (1995 C280) wrote:
I hear a constant pumping noise from the right back side of the car. Opened the trunk and removed the wall cover and the noise seems to be from a pump looking think with a few hoses connected to it. It sounds like a fan motor turning on and off every 5 seconds none stop.
Anyone here can help us??? Thanks!
Todd
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Joined: Mar 2002
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From: Belgium
Yep, it is the PSE (Pneumatische SteuerEinheit), a sort of vacuum pump (however it also has electric/electronic functions).
It is normal when you here it while locking or unlocking the car. When you here it more and/or longer than before you may have a leak. When you hear it while driving, it must be that air intake manifold pressure becomes too low. Under 300mBar (I do not know how much that is in American values, PSi's or whatever,...) the PSE "helps" to maintain all vacuum controlled things.
Patrick
It is normal when you here it while locking or unlocking the car. When you here it more and/or longer than before you may have a leak. When you hear it while driving, it must be that air intake manifold pressure becomes too low. Under 300mBar (I do not know how much that is in American values, PSi's or whatever,...) the PSE "helps" to maintain all vacuum controlled things.
Patrick
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Joined: Apr 2002
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From: NYC
red bicycle
Hey,
Thanks for your response. If you're saying there's a leak, is this something that needs to be replaced? I believe it was replaced on my C two years ago after the rear defroster stopped working...but I can be wrong. But I do remember that it was a $1000 part...
Todd
Thanks for your response. If you're saying there's a leak, is this something that needs to be replaced? I believe it was replaced on my C two years ago after the rear defroster stopped working...but I can be wrong. But I do remember that it was a $1000 part...
Todd
Senior Member
Joined: Mar 2002
Posts: 392
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From: Belgium
If you lock or unlock the car you should hear it only for a few seconds. If it takes longer there may be a leak somewhere, but that does not mean that the PSE itself should be replaced.
Rear defroster relay function is also in the PSE.
Patrick
Rear defroster relay function is also in the PSE.
Patrick
Thread Starter
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Joined: Apr 2002
Posts: 333
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From: NYC
red bicycle
Hey,
Thanks again. I hear the noise when I'm driving, but most noticably right after starting up...but that could just be because I'm not driving that fast at that point. I sometimes also hear it when stopped at a light.
I'm most likely going to bring it to my dealer to see what they can do, especially since they definately replaced the PSE two years ago.
Thanks again for your help.
Todd
Thanks again. I hear the noise when I'm driving, but most noticably right after starting up...but that could just be because I'm not driving that fast at that point. I sometimes also hear it when stopped at a light.
I'm most likely going to bring it to my dealer to see what they can do, especially since they definately replaced the PSE two years ago.
Thanks again for your help.
Todd
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Joined: Mar 2006
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vacuum leak 1996 AMG C36
I also have a pump noise coming from the passenger side trunk area, I feel the pump is ok, it's just compensating for a leak somewhere. My C36 only has 40,000 miles on it all vacuum connections look new. Short of going to the dealer is there anything i can do to find the leak? By the way, with the hood up and the ignition on, i hear a high pitched noise coming from manifold area. Thanks
