baldsparky

I have a w220 with airmatic suspension.
For almost a year now the pump as run frequently and is audible whilst driving.
My 1st test was the obvious check for leaks but I was confident that wasn't going to be a problem.
My reason is there have been occasions when the vehicle has been parked up for 3 to 4 weeks unused and during those times I measured the wheel arch to ground from 1st parked to return.
There was no drop on any of the 4 wheels.
Anyway, recently the raise function has shown that something is not quite right.
The vehicle raising light in the cluster stays on.
And although she does raise, it doesn' seem to be as high as I remember in the past.
I think its safe to assume that the pump is weak, and prevention is better than cure so have ordered a wabco unit from e bay for £218 (not a bad price)
Can you guys give any advice on pro's and cons for replacement.
Apart from reports of seized mounting bolts, it looks like a straight forward swap out for a competent DIY mech.
Thanks in advance for any advice, Happy motoring fella's.

wallyp

Too late for my advice to be of any assistance...

My first shot would have been to install a $25 piston ring in the compressor.

Get on YouTube and look at W220 compressor replacement and repair videos. Fewer surprises that way.

Take photos as you do the job, so that you will know how it goes back together. The support spring arrangement is not obvious, for example.

Check the compressor inlet air filter, replace if it looks bad. A standard in-line fuel filter works fine.

Not a bad job.

baldsparky

Many Thanks Wally,
Your right to late the new units on its way.
The car is a low mileage 1999 S320
53,000 with full dealer service history, and its the original compressor in there.
I considered a repair kit but what the heck, if the units out and in my hands,
For £200 a new unit after 15 years running seemed the better option.
As said I know I have no air leaks 100% confident of that.
All the signs of the pump getting tired were there over the past 6-9 months
So now she's not able to rise enough to extinguish the Vehicle Rising warning.
I decided not to let the poor old pump struggle any longer.
After all I would only have myself to blame for not taking preventative action now.
Of course for about £14 I will probably put a seal kit in the old unit and keep it tucked away in the trunk. (You never know)
I just felt the seals after such a long service life for the compressor was a half way house.
Hope that makes some kind of sense.
Many thanks for the reply.

cybertronicify

It might be a good time to replace the airmatic relay as well, you definitely don't want the old relay to stick and kill your new pump. Did you know, if you drive rough terrain or mountain roads, you will your pump faster?

baldsparky

Hella relay went in a week after owning the car.
And all thanks to reading through this great forum, which gave me the heads up.
I can see how rough terrain would have the pump working harder.
Doesn't help when the air release valve kicks in after parking up in my opinion.
Seems a waste of air pressure considering the next time you drive the air tank and pump have to work again to get the height back up.
I know its normal, and to be fair the air release only lowers the car by about half an inch, but never found out why its actually required to operate that way ??

Forgot to mention, a new relay is included with the compressor and its fitting is a warranty requirement.
Thanks again for all the replies.

cybertronicify

The car actually raises and lowers each strut independently so that even with passengers getting on and off, it will compensate by pumping more air into the specific strut. Thats why when you get off the car it will lower your side, or else your side of the car will be heavier.

My TYCO (Siemens) relay killed my pump after I got back from a road trip. It was a curvy mountain road and the car had 4 passengers. I think the airmatic pump was turning on and off trying to compensate and making the relay stick. After taking the airmatic pump motor apart, I saw complete destruction, there was a big blob of molten metal at the commutators. Surprisingly the airmatic pump head gasket was still in pretty good shape. I converted it to a high pressure water pump.

baldsparky

Just thought I would give an update.
The new pump is now installed SUCCESS !!

My only problem was I needed to replace the cradle mount as well.
2 of the 3 mounting rods sheared due to rust on the old unit, but no big deal once I replaced the mount.

I also replaced the springs and rubber mounting bushes for good measure.

Vehicle rises in about 10 seconds so spot on.

One other point the pump is still audible not loud but you can hear it running.
Its been discussed on the forum several times but I just wanted to say with everything new and double checked to ensure the pump is floating freely its confirmed my suspicion that a compressor good or bad is bound to be audible whilst running, its not loud but you can hear it humming away.
To be fair it lasts just a few seconds now the new units fitted.

Its a nice whirring hum compared to the old unit which clunked and clanked for ages whilst driving and as said only runs for a short while now.
Main thing is the vehicle rising goes out and it rises really quickly so very pleased.


Many thanks Guys