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I have a 2007 R320 with around 70k miles on it. Today the rear suspension sagged and the rear of the car went all the way down, both sides. The message on the console says it is trying to raise the car but it does not succeed. The front is OK.

Would this be an airbag or some other thing like the compressor or the block switch as someone has posted above?

This is going to be a DIY repair so I am looking at the Arnott air bags. I have replaced airbag springs in my Motorhome earlier so I kinda know what I am facing.

By the way, I am pretty sure I don’t have airmatic on it. How do I make sure I have airmatic or not?
 

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ok I made sure that I dont have airmatic by the fact that :
1. my car is missing height adjustment switch, right next to the seat heater button [is that really true?]
2. The front suspension struts are simple spring types....no air bag there.

I am looking everywhere in the official STAR service manual for my R320 but I cannot find a mention of a "block switch" anywhere.

I just do not want to order and replace the air springs and later find out that there was something else which needed to be replaced.
 

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Hello rajdude
I have only the back as air suspension, the front one are coil spring. So i dont have the airmatic switch for the height adjustment . So here is a picture of the back air bag.

[/URL] Uploaded with ImageShack.us[/IMG]
 

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my troubleshooting steps

Ok so I spent the good part of the day last sunday troubleshooting my air suspension problem and here is what I have found today. I am hoping that someone else troubleshooting this issue does not waste as much time as I did today.

First, I jacked up the car and took off the rear wheels. I sprayed the air suspension/springs with soapy water and turned the car’s ignition on….to the point where the console says “car rising, please wait”.
Nothing happened, no bubbles. Hmmmm…

Then I thought maybe I should look at the air compressor. For that I had to take the front passenger side tire off. I removed the plastic wheel well and found the compressor behind the headlight.

Got my wife to turn on the ignition while I felt the compressor. No vibration, no sound. So I thought the compressor was dead.

I took off the compressor’s power connection and put a meter to the contact….no 12 volts…nothing

I thought that the fuse Well then I traced back the wires to the fuse box on the passenger side of the engine. Using a multimeter I determined that the wiring is all OK. There is a relay which activated the compressor. The relay was also OK.

It was then when I realized that you need to start the engine to get the compressor to run! Yup…..I wasted a couple of hours figuring why the compressor was not working when the display was saying wait, car rising. In reality, it does not do anything! You need to start the engine first.

Anyway, after I started the engine, the compressor started running. However the car would not rise. I removed the thick white air hose from the relay/controller and measured the air pressure using a pressure gauge….it was not going above 15 PSI. The manual says that the air springs operate between 90 to 145 PSI.

Hence I need a new compressor.

I found an OEM one from e-bay at $455 free shipping. Ordered it. Once it comes in I will update this thread.
 

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So my fiance wasnt telling me that her car over night was lowering on the drivers side finally I drove the car to Tampa and I guess thats when everything went to crap the "Stop car to low" light came on. I had a few passengers because I was with the kids. Now the car lowers whenever there is passengers. Took the car to an indy and he said the compressors bad but is not sure if the bags are... (I was confused) He said we will have to change the compressor first and test it to see if the airbags are bad. I've heard tons of different things that can make it lower... Leak in the hose, leveling sensor bad, bad airbag... Now I know that the truck has a strut and airbag in the rear according to the pic below... Do I need to just replace the airbag or both.

 

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I just finished diagnosing this problem on my R320 ......you can diagnose what is bad by looking at my post above.

Basically it is easy to diagnose the compressor. Just put a gauge to it........it should read well over 100PSI......mine was only 15PSI.
Did your indy mechanic do that or is he just guessing? If he is just guessing it could be an expensive thing to replace just for nothing.

Maybe the airbags are bad instead....and he will end up replacing the compressor only to find out that it was actually the airbag which was bad.

There are only three things in this system:
1. Compressor
2. Valve
3. airbags

Sure there is electronics and height sensors...but they are not usually the problem. #1 and/or #3 is usually the problem.

I'd say first, put a guage on the compressor...make sure it is bad or good...then replace it only if it is bad.

By the way, if the airbags are bad.........make sure you replace both sides........they are around $330 online..Arnott/e-bay.




BTW, if only one side is going down.........I bet the compressor is OK..........that side's airbag is probably bad...........the hoses are made of plastic not rubber..........they probably wont leak. Just spray soapy water to diagnose....easy.......good luck!

So my fiance wasnt telling me that her car over night was lowering on the drivers side finally I drove the car to Tampa and I guess thats when everything went to crap the "Stop car to low" light came on. I had a few passengers because I was with the kids. Now the car lowers whenever there is passengers. Took the car to an indy and he said the compressors bad but is not sure if the bags are... (I was confused) He said we will have to change the compressor first and test it to see if the airbags are bad. I've heard tons of different things that can make it lower... Leak in the hose, leveling sensor bad, bad airbag... Now I know that the truck has a strut and airbag in the rear according to the pic below... Do I need to just replace the airbag or both.

 

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Thanks rajdude... I'm going to check it out, the car has got to the point where its doesnt even want to lift anymore... So i'm not sure if there is something else to replace, and I hate going to MB or an indy cause FL is so expensive with that stuff. Just for MB to look at my car is $165.00 and for an Indy to look at my car $95.00 and all their doing is looking at it. Not that I mind paying something if its worth it... But I feel its a rip off
 

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Hey I am all for Indys....in fact I never go to the dealer.

However, I usually end up doing all the repair work myself (sometimes I have taken it to the indy for diagnosis.....and once when it was the middle of winter and I could not handle the long repair outside {I don’t have a garage]

Anyway, I just repaired mine....more on that on a later post.

My car also was at the point that it would not lift anymore. However the difference between mine and yours is that yours sagged from one side first [that points out that an airbag was probably bad]. Mine...both sides went down at the same time.

I'd say check the compressor first...it is super easy! Just take off the right wheel, then the fender cover inside it...and boom...you see the compressor right behind the headlight.

Then start the engine and see if the compressor even runs [the car should say it is rising first for the compressor to turn on]. If it does not, maybe the relay got burnt out OR the compressor is bad.

Relay = cheap and easy fix
Compressor = $450 and still an easy fix...half an hour job tops.

If it runs....take a 12mm spanner and remove the white plastic hose, the thick one from the valve thingy. See how much pressure are you getting [while the compressor is running]. I had a pressure gauge from Harbor Frieght….30 bucks or something.

Maybe you could even put a finger to it and it should be able to generate a LOT of pressure….mine was pfftttt and no pressure.

So that is how you can check your compressor.

Good luck.


Thanks rajdude... I'm going to check it out, the car has got to the point where its doesnt even want to lift anymore... So i'm not sure if there is something else to replace, and I hate going to MB or an indy cause FL is so expensive with that stuff. Just for MB to look at my car is $165.00 and for an Indy to look at my car $95.00 and all their doing is looking at it. Not that I mind paying something if its worth it... But I feel its a rip off
 

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my update

Ok here is an update on my repair.

The compressor I bought from e-bay $455 fre shipping works 100% fine. It is made by the same company AMK which made the OEM compressor...looks identical too. Arnott sells it for $470 + shipping. Mine came in a box which said Arnott on the outside. Probably was drop shipped from Arnott themselves :confused:

But tell you what....easiest repair I did on this R320, I swear!

Diagnosis took me hours and the compressor replacement took me less than an hour….actually the replacement took just 15 minutes or so. Just three nuts and the compressor drops down. Two hoses come off easy. Most of the time was taken in re-installing the fender liner and the wheel.

After I installed it, the moment I started the ignition, the compressor started running. Within seconds the rear of the car started rising…and it has been good for the past 2-3 days.

I did spray soapy solution and checked for leaks before putting everything back together.

hope this helps someone. :D
 

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Now my fiancé is telling me that she has been riding with this for a few weeks now... Do you think that strut is bad? Is there a way to check?
 

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I was quoted 4500 usd for replacing left front.
This is including work and parts, here in Norway (Oslo)

I got a quote from Arnott
A-2587
$344.80 + $84.23 Shipping (2-3 days)

But this is only the "bag", will it be harder to change this, than the whole strutt ?
 

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Yes, NOK 24900.-, and according to the service manager is most of the cost parts, and hardly any labor!!

Anyway, if anyone have done the "bag only", I would be grateful if you could comment on hove difficult this would be.
According the Indie, there is a need to have some software to read out some level info prior to changing it, and re align after swap?
 

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Now my fiancé is telling me that she has been riding with this for a few weeks now... Do you think that strut is bad? Is there a way to check?
No the strut has nothing to do with the ride height. It is controlled by air pressure in the air spring.

That strut is just a damper.
 

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@Jay

Is your rear suspension bad or front? The image you have posted is of the front suspension. My comments are related to only the rear suspension.

My car does NOT have airmatic. Do you have airmatic?
 

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Can you reset the air leveling rear?

My 2006 R350 just developed the right side lean and it only has the rear air springs not the full Airmatic. It appears as if the left side is maximally inflated though. is there a way to reset the system to level back out and let air our of the left side. Or do I just need to take in to a repair shop and have them run a diagnostic. Seemed to have occured when the weather got colder this week.
 

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must change relay

For what is it worth...after I replaced the air compressor.....at the very first engine start in the morning......the console gives an error......"Malfunction" with a upwards arrow sign inside the R class shape.

I read that it is mandatory to replace the relay while replacing the air-compressor. So I bought one from the local dealer and replaced it today. The part number is A002 542 7619. Around $29.

Unfortunately the error message is still there.

Strangely:
1. The car's suspension works fine.
2. The error message comes only once....in the morning....it never appears again for the rest of the day.
It is almost seems like it is dependent on cold temperatures. Once the car warms up the error goes away.
 

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How do you check the psi of the compressor? I have everything off and dont see a guage/nozzle to check
There is no built in gauge. You have to buy one. I got one from Harbor freight...it came with the right adapters. I disconnected the white hose/pipe coming from the compressor to the "distribution block" ...and attached the gauge. Start the engine and read off the pressure. It should be over 150 PSI.
 

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Thanks Rajude, picking it up today... Changed the airbags and the car is fine, but still want to check out the compressor. Now I heard from a single person that I will have to bring it to an indie to have the car leveled, because I changed the airbags. How true is that? I thought the r350 came with an auto leveling system. Correct me if I'm wrong
 
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