S211 Air Suspension Compressor noise

[Paulo1967]

Today I became aware for the first time of a buzzing noise from the rear of my 08 S211. It seems to originate from the rear left, which leads me to assume it is the air suspension compressor. It runs noisily from when I switch the ignition on, until the engine is switched off. The car is not sitting low, and seems to ride normally. Anybody have any idea what the issue could indicate?
Thanks.

 

[zipdip]

Well it is strange that you say that the noise from the compressor is happening all the time,whats suppose to happen is that when you start the car it might kick in to top up the air tank,then it should stop until some air is used out of the tank,I suggest that you might have a leak on the system.

 

[Paulo1967]

Well it is strange that you say that the noise from the compressor is happening all the time,whats suppose to happen is that when you start the car it might kick in to top up the air tank,then it should stop until some air is used out of the tank,I suggest that you might have a leak on the system.

Thanks for the reply. I just tried it again on the drive, switched on the ignition but not the engine. As you say, it ran for maybe 30-40 seconds then stopped, but I don’t recall it being noisy before.
I’ll monitor this and see if it persists - earlier when driving it was buzzing all the time for about 30 minutes.

 

[mersum1es]

There is a 30 seconds time limit when compressor is switched off in safety reason (not burning electric motor), usally such behavior is due to leak somewhere, or too worn compressor unit (pump cannot reach required pressure). Even pressure is not high enough, it can still be enough to maintain car height. Reservoir pressure is around 15bar when struts need ~under 5 bar to keep car in balance,

 

[zipdip]

If you go to a MB indy they can run a test scan on the compressor they empty the air tank and then start the compressor it has a set time to fill the tank,that shows if the compressor is worn and needs replacing,but that fault nearly always puts a fault up on the dash,because you say the car is at the right level,my bet is that there is a leak between the compressor and the tank,it could just be a connection leaking,but the longer you leave it will wear out the compressor.

 

[Wearsthefoxhat]

The compressor for the Airmatic on my S211 is in front of the passenger side front wheel behind the bumper…

 

[zipdip]

The compressor for the Airmatic on my S211 is in front of the passenger side front wheel behind the bumper…

The fact that the op said the noise was from the rear,I assumed he has a estate S211.

 

[Wearsthefoxhat]

Fuel pump perhaps..

 

[Paulo1967]

There is a 30 seconds time limit when compressor is switched off in safety reason (not burning electric motor), usally such behavior is due to leak somewhere, or too worn compressor unit (pump cannot reach required pressure). Even pressure is not high enough, it can still be enough to maintain car height. Reservoir pressure is around 15bar when struts need ~under 5 bar to keep car in balance,

Thanks. Reading the replies I am beginning to think a leak in the system or a failing compressor is likely. It obviously tops up the tank when the ignition is turned on,

 

[Paulo1967]

Thanks everyone for your advice. I will get it booked in to be looked at, hopefully it’s just a connection, but who knows what world of pain I could be facing

 

[zipdip]

Thanks everyone for your advice. I will get it booked in to be looked at, hopefully it’s just a connection, but who knows what world of pain I could be facing

Well at least your car is level and showing no sign of dropping,if it is a leak between the compressor and the tank then it will only be a small pipe fitting to mend it,as always share your pain with us we like to hear what you did to fix this fault.

 

[Paulo1967]

Well at least your car is level and showing no sign of dropping,if it is a leak between the compressor and the tank then it will only be a small pipe fitting to mend it,as always share your pain with us we like to hear what you did to fix this fault.

I’ll let you know. Booked in for visual inspection Friday.