S211 Compresser keeps running, going to burn out I fear.

[ThamesEstuaryMan]

The air suspension compressor on my EClass 2007 has started to run immediately I start the car, and stays on much longer and comes on much more frequently than it has in the past.
Ive changed leaking air rams in the past when the rear of the car has sagged but this is different. The car seems to be at a good height, nothing is sagging, and we’ve had it up on a lift today and can’t detect any leaks (nothing hissing). I’m wondering if the switch that detects the ride height is playing up but don’t know where that is.
can anyone offer any advice on what could be causing this, and where the ride height switch is to be found please. I’m concerned the compressor is going to burn itself out.

 

[malcolm E53 AMG]

It may be that the air pump is tired and not working at the right pressure there is a piston ring repair kit available from:

http://bagpipingandy.com/

 

[Wearsafoxhat]

The three ride height sensors on my MY2005 E class are one each above the front wheel, visible if you lift the car slightly to see above the wheel and the rear one is above the diff.
iirc the compressor has an output too, which may continue to demand that the compressor runs.
perhaps the relay in the front SAM is sticking, cheap fix if it is..

 

[V12cat]

It may be that the air pump is tired and not working at the right pressure there is a piston ring repair kit available from:

http://bagpipingandy.com/

2 1/2 years ago I used one of his kits on my W220 S500. Worked really well and is still fine now.

 

[ThamesEstuaryMan]

The three ride height sensors on my MY2005 E class are one each above the front wheel, visible if you lift the car slightly to see above the wheel and the rear one is above the diff.
iirc the compressor has an output too, which may continue to demand that the compressor runs.
perhaps the relay in the front SAM is sticking, cheap fix if it is..

What’s SAM please ?
if the relay is cheap n cheerful, might be first thing for me to try, then a piston ring kit.

 

[Wearsafoxhat]

The relay is in th big box of electrics, engine bay in front of the driver.. iirc the relay is the small green one towards the back. £6 from the MB parts counter. There might be a diagram showing its position.
The compressor repair kit worked for me too, easy to change the piston ring inside, difficult to get the compressor back in place, working on the drive.
Worth buying a new filter, filter housing and the two rubber tubes that connect it all together, again cheap from the parts counter at MB.
Contact MB in Newcastle via their eBay site and order from them… good guys and fair price..