JMorrison

Can anyone Help.
Strange things going on.

New to me 07 GL 320
Rear air bags replaced by previous owner.
Front air struts I just replaced. (Right front was leaking and front would sag overnight) Replaced both and now the vehicle stays inflated overnight but>>>>>>

When I start up in the morn air compressor comes on.
Fills up and then seems fine when sitting.
When I drive, air compressor might come on and go off continuously for 5 minutes (fill up, shut off then come back on within 30 seconds or so)
Sometimes it goes off and stays off and everything stays inflated for 5 minutes.
Sometimes compressor overheats and goes into cool down mode.

A few times the front end just dropped within about 2-3 seconds when at stop or driving. If I shut down the vehicle then start back up, compressor (if cooled down) would come on and fill er up.)

Compressor is noisy so I am replacing that tomorrow but is there likely other issues I should be looking at? Front leveling sensors?? distribution control valve???

Thanks for any help.

I will post updates as I learn the system.

sclasspilot

I have an 08 ML320 but the air suspension system is the same.

It sounds like you have an air leak or the compressor is not producing sufficient volume. The compressor shouldn't operate each morning, because there is no air consumption overnight. You said the car stays up, which means the air tank is signalling low or empty after sitting for a while.

Check for a leak from the tank or airlines, or failed non return valve.

I'd strongly suggest testing the compressor before replacing it. There is a test in XEntry/Star where the compressor must achieve a certain air tank pressure level within a set time period (40 seconds from memory).

Regarding the "front end just dropped within about 2-3 seconds when at stop or driving". This is normal behavior as the computer periodically self levels. It can go slightly up or down over 2-3 seconds.

abtabor6

You have a leak somewhere, I know this doesn't find it or you have a sticking relay.

the relay is a square in size and is in the front engine fuse box. Price is around $30.

JMorrison

So Here is my saga over the last year

Replaced front struts and bags. Solved the problem for a little while

Replaced rear struts and air bags. Solved that problem..... For a little while.

Compressor was just plain worn out from all the friggin use.... Replaced Compressor with cheapie on ebay…Solved the problem for a little while.....

That compressor failed.... Replaced with an "OEM" compressor on Ebay for pretty penny. Concerned when I got it and it did not say Arnott anywhere on it but put it in as we needed the car.....That worked for 60 days and crapped out...…

Still fighting with ebay, paypal and etc to get my money back..

Replaced with OEM arnott from my local distributor. IT has a lifetime warranty and comes with relay....That worked some but seemed like I had bad connection at compressor as sometimes compressor would not come on and front would sag after a few days. Wiggle the wires at compressor and compressor would come on. Took everything apart cleaned connections and put all back. Still same issue.

Then I found that the wiring harness that I was wiggling on was rubbing on a sharp edge of the inside body and one wire was chaffed and touching ground. Cleaned that up inspected all other wires and all looked good. Now the compressor wont come on at all!!

This thing is a bear.

Have power to the relay sometimes. Have power to the fuse sometimes.
It is very wonky and I am taking to local Mercedes mechanic to have him go thru it.

I have become pretty disheartened with the vehicle and esp. the airmatic system.
Had Prevost motor coach growing up with air bags and full air ride suspension and it was a robust and easy to test and diagnose system.(500,000 miles with minor issues) This thing is a first class nightmare!!!

Will post update at some point.

Cheers.

kombifan

rustybear3

....and that, my friends, is one of the main reason I opted not to get the system on my new E450 CAB Mercedes. I had one years ago on a Cadillac Eldorado that was an absolute nightmare.

It's a firmer ride, then the standard suspension, and the negatives outweighed the positives IMO....especially the repair costs.

kombifan

DansGL

It sounds very much like the pressure hose coming from the pump. It often gets a tear or hole in the bend. Open up your right front wheel well liner and inspect the hose.

StephenPage

Did you ever identify your problem? I noticed my 2012 GL450 does something similar. However, the ride height after sitting overnight is perfect. Yet, the compressor usually runs for about 5 seconds when pulling out of the driveway, then again at the end of the street. I'm not sure how much it's cycling while driving because of road noise. I've used leak detector at all connections and don't see anything there. All four bags have been replaced and the pump still cycles.