scrowley

Hello. New to this forum and the w212 model. I have a 2010 E550.
The air compressor for the oem air ride doesn't seem right. The compressor runs very loud like the isolators must be bad. Also runs a lot.

Every time I start it it turns on and off for a few minutes. When in sport suspension it runs less but still runs.
It also blows off air from the trunk area when it not even running or on. If I even open the door a release valve lets out air...sometimes a little sometimes a lot.

The car is not sagging over night either. Seems like its releasing air pressure then when I get going again the compressor runs to re fill.

Any ideas from the pros on this site? Where exactly is the compressor located?

Thanks in advance for the help. I'm not a noob to autos so this shouldn't be a pain staking thread

KEY08

That's exactly how my 2010 E550 acted. Is this car new to you? What is the issue?
it runs when you start the car in the morning and farts a lot when taking a nap. Compressor is in the side of the trunk area.

scrowley

Yes I just bought it a few weeks back.

Exactly....runs and farts. Is this normal?

Only thing is the compressor is very loud. Like its not isolated with rubber bushings or something. Almost vibrates the hole car.

thefisch

Running and farting here too.

No vibration though, at least that I can feel. Guess I need to add some quarters.

KEY08

You are killing me Fisch! It is a whining sound and should not be noisy as you describe. The pump is $500-$600 I think.
farting totally normal

Abrown3mtg

Compressor is definitely audible. If car is sitting level and not losing pressure from the system overnight I wouldn't be concerned. The farting as referenced is the car self leveling on a not flat surface from what I've read when parked. Sounds pretty normal without hearing the compressor running in person.

scrowley

Thanks for the input. I'm guessing something is defiantly up with the compressor or mount. Almost sounds loose. Its not a constant hum from the compressor engine. It gets loud then quiet, as well as high and low rpm. Mercedes wouldn't make it as loud as mine is I don't think

Is the compressor mounted on the driver's side of the trunk? I will get in there and check it out.

KEY08

Yessir. Pull out the side panel.

kajtek1

The compressor rebuild kits are about $15, but noise might indicate something else.
I could never hear my compressor over engine noise, unless I would stick my ear to LF fender.
When compressor runs a lot - that indicate a leak. Good system should run the compressor only when you load the car, or when temperatures drop, costing lower air pressure.
If you have scanner to monitor the pressure build -up >> you can narrow the problem, but other than that I would start with compressor rebuild, new air filter, baking the drier granules and go from there.
I made topic in W211 section how to do it.

scrowley

Ok. Thanks for that info.

Well I can hear it over the engine, radio going, etc. Its loud.

I have a obd2 scanner. Nothing special but it has quite a few options.

Can you please give me a link to your compressor refresh?

Abrown3mtg

Compressor is on the bottom of the car drivers side. The tank is behind the panel in the trunk on the drivers side.

How many miles are on the car? Did they advertise new airmatic components when you bought the car or do any of the struts or air springs look new? I ask because if there had been a prior leak, the compressor would run a lot more to compensate and could have burned up a bit. Perhaps go test drive a similar model year car to yours as a baseline. I've had several vehicles with air suspension (a different mercedes, audi, and range rover. This one is by far the noisiest. I believe the fact the compressor is under the car and not insulated it echos a bit if that makes sense?

scrowley

Nice. Thanks. So the compressor is under the car.

The car has 90k. On Carfax it was at the dealer at 87k. All the struts look to be original oem. No signs of a new strut.

I hear you on the echo since its not covered. Its quite loud. If I don't see anything visual I would guess the compressor is bad.

That's weird on the non insulated exterior mount. My last BMW X5 had bags and you literally couldn't hear that compressor run as it was under the spare tire and well insulated.

belarus27

compressor does make a sound , but when in the car with closed doors , MAX i could hear is a very very slight buzzing sound , and thats if i actually pay attention.

and if its not sagging overnight you safe, should be lucky.
but if its extremely loud , the problem might be in the compressor itself. (but again , its normal for a compressor to make some noise/sound)

p.s. might wrap that in something sound proofing material to eliminate some ....just an idea

kajtek1

https://mbworld.org/forums/e-class-w...e-rebuild.html

thefisch

That's not normal. I don't recall ever hearing it when the car is running. Only time I hear it is when car is parked and I open the door. Even then it doesn't seem loud to me.

KEY08

No, it is a pretty quiet whine/whirring noise if I remember.

2012 merc amg

90k Miles, if the original pump it's time for replacement more than likely. Check ebay and have it installed by a independent mb mechanic, be a lot cheaper than the dealer getting the part and doing the job.

scrowley

Just an update. I pulled the dust shield off of the compressor and sure enough there is a rubber isolator that is half missing which was allowing the compressor to bang against a metal support bracket. So the compressor was loose after all. I rigged it tight with some zip ties for now until I install a new oem bushing.

Should be nice and quite as you guys say they are.

Thanks for all the reply's

KEY08

Nice. Seems like it's functioning properly also, good deal.

The G Man

But it doesn't solve the problem why it runs a lot, I would keep an eye on it, you might have a leak. You might end up killing the compressor if it runs too much.

scrowley

It runs much much less now that's it's very hot out... so maybe a very small leak I'm guessing.

kajtek1

Small leak is still going to kill your compressor in short time.
Well holding system should come only when you load the car heavier, or with temperature change.
I spend some time on my wagon and the supply system hold 120 psi overnight.
There was self-check at each engine start, but run time was 2-3 seconds.

scrowley

The car seems too let out quite a bit of air when I shut it off. Pretty loud blow off valve noise. Sometimes does it once or up to 3 times. Few seconds each time. Idk.
I would have to hear another at to make a determination.

I will take a video tomorrow and post it up.

scrowley

Well the car sags about 5/8" in the rear only overnight.
Like 10 hrs.

Any good tips on troubleshooting? Using in line pressure gauges, etc. ?

kajtek1

5/8" could be temperature-related difference.
If you really want to check the system, read reply #9