Hey there!

With colder Midwest temps in the winter, I expect the Airmatic system to run a little more when I transfer from the heated garage into the great outdoors. However, there are times that it seems that the GL's Airmatic system runs a long, long time. The problem is, I don't know what is truly normal yet as this is my first GL and my first winter with it.

So...to get a feel for this here's a baseline question for folks. If you press the Airmatic button to lift your GL, how long does your pump run?

In addition, it feels that the pump is rather loud (to me) and reminds me of the sounds from all the old-school compressors we've had plugged into our lighters to refill tires. I've heard some say they are loud, I've heard some say they can't even hear theirs. I've also heard that replacing the mounting hardware can lessen or eliminate that noise.

So...when your Airmatic pump is running, do you feel like you're airing up tires or do you really notice?

Thanks in advance for all the great insight!

Peace...Away...

 

 

My apologies...useful information to have of course.

In an 11 mile trip in the morning, it will fire up in the morning for maybe a minute or two. On the commute it may fire up 2 or 3 more times for maybe 30 seconds.

I have no noticeable sag on any corner. I've checked all four with a live data scan tool as well and they seem quite solid.

I have read that sometimes replacing a relay and the Airmatic filter can help. I have replaced the relay (cheap stab) but not yet the filter (need warmer weather for that repair).

 

If you have the capability run the pressure test in the reservoir for rhe airmatic pump its probably not able to hold it anymore...could also again be a defective relay

 

Man...talk about something hard to find online...the Airmatic reservoir for a 2009 GL450.

Any insight into where I should start the search. I have a couple guesses, but I'm not near the GL right now.

I'm also not clear on how best to run a pressure test on the reservoir. Input here would be appreciated.

I did replace the existing relay with a new Hella relay. The runtime and results are the same with each; either meaning they are both good...or they are both bad. I'm opting for good.

 

 

That was my first guess based on the look of the replacement and what I've seen in that area of the GL. It feels like we are barking up the same tree.

In my mind (maybe too simple at times), if there is no sag the bags are solid. I've left it sit for about a week just to test the sag as well as the scan tool. If bags are solid, maybe the relay is faulty and can't determine when to turn on and off. Replacing the relay caused no change in behavior; giving me the logically impression that the relay (old and new) is solid. My thought was also that maybe there was a leak in the line or in a fitting attached to one of the struts, but this would logically cause the Airmatic to run more than it does in my opinion. Finally, with the rather loud sound of the compressor (like the old ones used for tire inflation in the day), I can't help but feel it may be on its last leg.

Other than the disassembly of the front end to get to the Airmatic pump (exaggeration), it seems like a reasonably easy and inexpensive next step.

 

 

Found a couple places for $325. Feels like a reasonable price and the most likely candidate to solve the issue.

If you happen to have done this before, did you find that you needed any specialty tools for the project? I've got a massive collection and the GL seems to be helping me add to those.

Also, if you have gone through a replacement, did you find that the newer Arnott was more quiet?

 

i used arnott for replacement they use the same manufacturer that mb uses and comes with a lifetime warranty

 

Poking around online (dangerous at times...yes) I noticed that many people who experience the noisy pump that I have are doing piston ring replacements as opposed to replacing the entire compressor. What I am struggling to determine is whether or not worn piston rings would actually cause the compressor to run longer and more often than what seems normal. Since my issues are both the noise and the run-time, without any air spring sagging, it does feel like this area is the likely culprit.

Looking forward to thoughts on worn rings and that potential relation to extended run-times of the compressor...

Thanks...Away...

 

Start with the less expensive route first, replace the air filter and inspect the intake line. The relay rarely goes bad as do the sensors, but you have no sag so... at times the solenoid block might be the culprit. OR you have a leak in a bag that is only happening upon driving. When the vehicle is parked the bags overlap on them selves and could the leak could be contained within the overlap thus not losing air. When you drive the leak is exposed enough for the pump to start and compensate for air loss. Could be possible or maybe not, you have to start somewhere and go through the system, start with the intake line and filter, that needs to be done regardless, then check the bags by lifting the car and spraying them with soapy water. Spray the solenoid block as well while you have the inner fender off. Pumps go bad only if they have to run to compensate for a leak. My pump was replaced with an Arnott and 50K later it's still good. I replaced the solenoid and intake line/filter recently after the pump started whining. It's a lot of work but it's just what a shop would do.

 

I wonder if this compressor and shocks are same as say a w221 S class.

 

Your pump is on its way out. Its about time anyway.
If it can lift it when you press the up button in control panel, it doesn't need replacement, YET. But it is going. I just replaced mine about a month ago07 GL 450 @ 84K miles. I didn't search around for piston ring replacement as I wanted to just get done with it. I got one from FCP euro due to their lifetime warranty. Mine was running loud and longer for 4-7 months and finally it started giving Airmatic malfunction error on highways. And, it won't lift the GL all the way up when I would press the button to increase the height . It would shut down in middle with error that "compressor is cooling down".
The new compressor is very quiet.
I didn't change the relay as I knew there is nothing wrong with it.
No specialty tools required. If you do end up changing the piston ring only, that would definitely be cheap and better option. Do make a DIY so that we can learn from it.

 

As I think more, I struggle to believe that piston ring wear alone would cause the compressor to run more often or longer periods. Admittedly, it could be less efficient and maybe run longer, but not necessary more often. At around 90k miles, it seems like a reasonable time to expect this piece to start failing.

I've not run into any real issues or errors, so I'm a little ahead of the full failure timeline. Or so it seems...

 

maybe it is just fine. without star/das you have no idea anyway.

wait until you start getting "compressor cooling" messages- then replace pump.

 

Well, If you have been around this forum for few months, you must already know that Alx is the person to listen to !
Worn piston rings will make it run longer and louder. Frequency is probably the same but now that it is loud and runs longer, you are noticing it more. As he said, if no errors, don't worry for now unless corner(s) sagging. In which case, it won't be compressor anyway.

 

Certainly seems reasonable. The concern is that in a month or two we'll be strapping 6,000 pounds to the back and heading out camping. Somewhat concerned about a failure 1/2 between here and there or there and here...

Know what I mean?

 

A quick follow-up that may help my understanding...

If/When the "compressor cooling" messages begin coming, does anyone have a general sense (or guess) on how longer after that message one could expect the compressor to fail in keeping the suspension upright? This could provide a little more--or less--comfort in waiting for the messages and subsequent failure.

Thanks...Peace...Away...

 

 

Have heard several recommend lifting the Airmatic to check for leaks. I will do this when I get home today (hopefully) with the bubble test. However, I decided to bring scan tool to work with me (Sam not in my budget sadly), lift the GL and then will check a couple times through the day. I took some snaps of the scan tool's readings and the stated level of the right rear is notably lower than the others. It does show the right rear lower, and it measures slightly lower between wheel well and tire, but not sure it's a true 20mm. Here are the shots...

 

Quick Update...

Going back to the GL about 7 hours later all of the voltages were the same and the heights were slightly higher. When I arrived at the office it was about 33 degrees, but at the time of the second check in the afternoon it was around 55 degrees. Seems that the bags are pretty solid.

 

To all that provided thoughts and input, thanks.

Replaced the compressor Friday afternoon. I pulled compressor run time from scan tool before and after the replacement. Before, the compressor used to run about 20 to 25% of the time over the last couple weeks. Now it runs right at 5% of the time. This feels much better.

Thanks again!

Peace...Away...

 

 

With the compressor run time that you logged, does that mean that the compressor was not running as efficiently (worn piston/rings/whatever) as it should... so it was running longer?

GL450x164... Just curious, why did you mention the reservoir again? Is there more to this? My pump is doing the same thing - it's a little louder than normal and seems to run a little more often/longer than I "think" it should. I would think it's the compressor on it's last legs and not the reservoir. I mean, if the reservoir had a leak, the compressor would be running A LOT more, right? I am positive it's NOT the bags. Reading through your thread, Maine, it seems like pretty much a dead-on comparison to my situation.

Where abouts in Maine? I, and other family members, have cottages in Cushing and Friendship (coastal).