Intermittent Whirring from Passenger Rear Wheel Well
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1999 C43
Intermittent Whirring from Passenger Rear Wheel Well
First post to the forum. I have a '99 C43. Drove it yesterday and noticed an intermittent "whirring" sound coming from the passenger side rear wheel well - from that side of the trunk. Sound occurs whether or not the car is moving. The noise is not unlike the sound made by the vacuum pump when unlocking doors. I'll get screwed if I take it to the dealer. I no longer have an independent mechanic I trust.
Any ideas what this is? Thanks!
Any ideas what this is? Thanks!
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Joined: Mar 2005
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From: America
1999 C43 AMG, 2005 E55 Wagon
It's the auxiliary electronic vaccum pump mounted behind the filler door. When you have a leak in the vac system (door locks or AC vent actuators) this pump will run to compensate for the leak.
I've seen it work fine that way for 5+ years with no problems and I've seen them burn that (expensive) pump out within 1 year of the leak. Either way, find the leak and fix it before the pump burns out and you lose door locks and control over the AC vents.
I've seen it work fine that way for 5+ years with no problems and I've seen them burn that (expensive) pump out within 1 year of the leak. Either way, find the leak and fix it before the pump burns out and you lose door locks and control over the AC vents.
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1999 C43
"Either way, find the leak and fix it before the pump burns out and you lose door locks and control over the AC vents."
Excellent. Thanks for the speedy response! Any advice on finding the leak in the system? I don't have one place that's flat-out not working. Though, over the years I've had issues in several parts of the system.
Excellent. Thanks for the speedy response! Any advice on finding the leak in the system? I don't have one place that's flat-out not working. Though, over the years I've had issues in several parts of the system.
MBWorld Fanatic!
Joined: Mar 2005
Posts: 2,418
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From: America
1999 C43 AMG, 2005 E55 Wagon
"Either way, find the leak and fix it before the pump burns out and you lose door locks and control over the AC vents."
Excellent. Thanks for the speedy response! Any advice on finding the leak in the system? I don't have one place that's flat-out not working. Though, over the years I've had issues in several parts of the system.
Excellent. Thanks for the speedy response! Any advice on finding the leak in the system? I don't have one place that's flat-out not working. Though, over the years I've had issues in several parts of the system.
You could pull the fuse for the AC blower motor, turn the key to ON, and test the door locks and AC vents and quietly listen for hissing sounds around the cabin/exterior.
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1999 C43
@Sulaco - Thanks for your help! I checked both front seats, and both had open vacuum lines. The auxiliary pump is no longer running... as frequently. I suspect I have an air leak in at least one of the air bladders in the passenger seat - or another connection is loose. If I fully inflate the support that extends the front of the passenger seat (not sure what that's actually called) the pump stars running intermittently. If that adjustment is fully deflated the pump runs far less frequently. There might still be several small leaks in the system.
One thing I've noticed is that the supports in the driver's seat inflate when I'm starting the car. I don't remember that happening in the past. I assume they stayed inflated. Just another indication that there must still be an air leak in the system. I have not noticed any hissing sounds. I'll just have to continue the search.
Thanks again! This forum has been a great resource.
One thing I've noticed is that the supports in the driver's seat inflate when I'm starting the car. I don't remember that happening in the past. I assume they stayed inflated. Just another indication that there must still be an air leak in the system. I have not noticed any hissing sounds. I'll just have to continue the search.
Thanks again! This forum has been a great resource.
MBWorld Fanatic!
Joined: Mar 2005
Posts: 2,418
Likes: 194
From: America
1999 C43 AMG, 2005 E55 Wagon
@Sulaco - Thanks for your help! I checked both front seats, and both had open vacuum lines. The auxiliary pump is no longer running... as frequently. I suspect I have an air leak in at least one of the air bladders in the passenger seat - or another connection is loose. If I fully inflate the support that extends the front of the passenger seat (not sure what that's actually called) the pump stars running intermittently. If that adjustment is fully deflated the pump runs far less frequently. There might still be several small leaks in the system.
One thing I've noticed is that the supports in the driver's seat inflate when I'm starting the car. I don't remember that happening in the past. I assume they stayed inflated. Just another indication that there must still be an air leak in the system. I have not noticed any hissing sounds. I'll just have to continue the search.
Thanks again! This forum has been a great resource.
One thing I've noticed is that the supports in the driver's seat inflate when I'm starting the car. I don't remember that happening in the past. I assume they stayed inflated. Just another indication that there must still be an air leak in the system. I have not noticed any hissing sounds. I'll just have to continue the search.
Thanks again! This forum has been a great resource.
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