minus13

So, I've got a new one (maybe) for you guys.

I walked into my garage and noticed that the front left corner of my GL320 was slammed. "Great", I thought, "time to replace the bags." I had to make a trip that day, so I thought I'd break out the soapy water, find the leak, and patch it to hold me over while the new parts came in. I pulled her out of the garage and drove her to the detached garage where all my tools and equipment are. When I pull in to the detached garage, the bag is fully inflated (no surprise there if it's a slow leak). I turn the car off and hear air escaping pretty quickly, but the sound wasn't really coming from the front, left wheel well. The bag is slammed all the way down by the time I roll out the jack and jack stands. I don't really think much of it.

My next move is to start the truck again and raise the vehicle by pressing the "raise" button in the interior of the vehicle so that I can chase the leaking air sound again. I'm not sure that greater height is achieved by blowing up the springs (because that doesn't make sense to me), but just in case it did, I thought that would give me a few more seconds to figure out where the leak is located. Once she got all the way up, I turned the car off. I couldn't detect a sound of leaking air. I sprayed soapy water all over the bag - nothing. I resolved to just ordering new bags, so I buttoned her up.

When I started the vehicle anew to move her back to the attached garage, I pressed the vehicle height button again to lower her. She lowered fine. I parked her in the attached garage, checked the bag when I got out, and everything seemed normal. There was no leaking sound and the vehicle remained at the proper height. I drove the car all weekend. No problems at all. When parked, the vehicle maintained its correct height. It seemed the a valve was stuck open. It couldn't be that the bag had a leak. However, Monday morning rolls around (about 3 days from when I first discovered the issue), I go out to the garage, and I see the the front left is slammed to the ground again. I repeat the same procedure as before, pressing the vehicle height button, letting the vehicle raise, dropping it back down, and again, air holds.

Air will hold for days, but then suddenly, it just slams back down. Something else is going on. The bag isn't leaking. Could this be a defective/broken valve block? What's going on here? I'm a little confused and I'm thinking I should just change the valve block as a matter of course to see where that leads. Your thoughts would be greatly appreciated.

Dan_Benz

Having the same issue with ours - 2007 GL450 with 120k miles. Rear Passenger Side (PS) bag slamming itself after sitting for over 15-20 minutes. We will come out of the store and its down, but sometimes it isn't, pretty crazy. I think it's a given that the rear PS bag needs to be changed, I really didn't need to call the MB dealership for them to tell me that. Was planning on tackling the problem when we changed both axle airbags, but money has been tight the last 9 months and we aren't seeing any positive things happen that are helping out, either. When it rains, it freaking floods around here lately.


So the new thing is the ESP is engaging when I make left turns. It doesn't matter the speed, just as long as I get some PS g-force going, the yellow exclamation alarm in the dash starts blinking and you can fell/hear the brakes trying to compensate for a slip that isn't happening. So I tried a little experiment last night. We live on an Army Post where the speed limit doesn't go over 35 much, so last night I lifted the vehicle and headed to the store on the other side of post, about 20 miles round trip. With the vehicle lifted, absolutely no issues at all from the ESP. Even tried some extra g's (more than I probably should have while lifted and top-heavy) in the left turns, but still no problem. Returned to the house, and let down the suspension, walked out this morning and rear PS tire is slammed again. Ok, whatever. So the wife took the Benz to the grocery store this morning, and behold, same problem.


Gave the MB Dealership a call, and of course, they said it's the air bags and they need to be changed. Only $4k, no problem, right? But I'm wondering, if I change the air shocks (which I would buy the Arnott remanufactured shock assembly and pay a shop to install) do I risk still having an issue from the ESP? I am planning on changing the sway bar links also, just because our GL450 has 120K on it and it's probably time, and I want to rule out any body roll issues.


So I guess my question(s) is, am I missing anything here? Should I look into changing more parts to ensure the ESP problem is fixed? Have you had any updated information or can you update me on what you did to remedy the slamming issue? Lastly, has anyone else out there have any information on another issue I'm not considering here? Thanks for the help - Dan

minus13

Our issues sound different. I don't lose air in 20 minutes. My bags will stay up for days, then suddenly, it will fall down quickly. Something else is going on for me.

Dan_Benz

Sorry, I should have been more clear. Sometimes the bags will drop in 15-20 mins after parking the vehicle, but mostly the rear PS is normal. It's pretty hit or miss as to when the issue arises, no apparent pattern or linked to any other events.

minus13

I think I'll change my valve block and take it from there.

alx

this

minus13

Thank you, sir. Changing the valve block seems like the most logical choice to me. Of the compressor, bags, and valve block, it is also the cheapest.

bha

minus13, how many miles on your truck?

At somewhere around 140k miles one of my fronts failed. Replaced both
Less than 5k miles later the rears started leaking. Replaced both.

Total time to replace all 4 is maybe 3 hours if you have all the tools and work without taking any breaks or stopping. I could probably rush and do it all in 2.5 hours. Assume 4-5 hours and you'll be done early

The reason I point this out is if your truck is over 120k miles or so, try the valve block but if that doesn't fix it just replace both front struts. And get ready to do the rears.

At a cost of approx $300 per front strut (and I think the rears were $300 for both) it's totally worth it.

My front strut started doing something similar to yours. It would sometimes leak and other times not. I suspect there was a crack and depending on how the bag was positioned/inflated/etc it would either leak or not. It could sit for few days and not leak, but other times it would be driven and leak 12h later.

Try the valve block first, then replace both front struts if that doesn't fix it.

minus13

See, that's just it - I'm only at about 83,000, which is a lot, but I expect a little more out of these bags. Nonetheless, it doesn't sound like an air spring issue. The bag is holding air. Something is causing it to release the air intermittently. I am thinking that I either have a malfunctioning valve block or a malfunctioning level sensor.

I can change out these springs/struts/shocks with my eyes closed. I have already done the job on an R-Class. It won't be much different. With that said, I don't want to replace parts just to replace them.

Thanks for the input. I appreciate your help.

bha

Agreed. It is a "possibility" that it could be struts, but with your mileage that possibility goes out the window.

You're right about the valve block or level sensor.

If you have DAS/STAR you can wait till the car drops and query the left/right level sensors. If they report back the same (or very close height) yet the car has dropped on one side, it's the level sensor. Not sure how you can do it without DAS though.

If not too expensive I'd start by replacing the valve block. I know it's a guess and I hate to throw parts at things, but based on what you have said, the problem can only be 2 parts:

Valve block
Level sensor

Replace the block, then if the problem goes on, replace the level sensor. Valve block is most likely so start there.

I haven't heard of MB's ever having valve blocks replaced (for Airmatic anyway. ABC is totally common). But my mechanic told me a while ago that he replaces them all the time. He probably knows better than I do...

minus13

Can someone tell me what exactly is happening when the vehicle height is raised? Where is the lift coming from?

N_Jay

Air pressure in the air bladder (Air spring).

minus13

Now I'm almost certain that it is a sensor or valve block issue. It's odd to me, though, that more air in the bladder is how it is raised. I would think that doing that would also elevate the effective spring rate. Interesting -

N_Jay

All depends on how it is designed.


If both settings are in the normal range, the dampening rates may not be much different.

Shellbmb

Digging up an old thread.

I came out today and my right front was "slammed" much lower than the other 3 wheels. My wife had parked that particular tire on a little step or curb in the driveway.

I unlocked the car and it immediately inflated to the normal height. Drove it around for a while and it seemed fine.

Is this a sign of more problems to come or just an isolated incident caused by parking on an uneven surface?

Thoughts?

2009 GL550 with 97k miles on it.

minus13

I would recommend replacing your front two bags and shocks out with new bags and shocks (Bilstein) and changing out your shocks in the rear as well (also Bilstein). If you wait much longer, you'll be changing out your compressor as well risking leaving yourself stranded in likely the most inopportune time.

PartsGeek dot com

bha

I agree with this statement.

At 100,000 miles you're close to the service life of the air bags/struts anyway (they fail at 120,000 miles in my experience).

In the next 20-30,000 miles you'll be replacing all four corners anyhow, so just do it now and save the hassle. You can buy Arnott parts now rather than being towed into the dealership which will save a lot of money. And as minus13 points out, you'll save a compressor ($400 I think).

Parking the way you did shouldn't cause one corner to drop. Something is wrong with the strut.

One thing I should point out is that a leak doesn't appear the same way every day. It might drop daily for a few days, then not drop at all for 3 or 4 days. That's what happened to me. WHen I started dropping again, I ordered new struts right away.

It seems that the suspension has to be in a specific position for the crack to open up. The next day when you park (maybe at a different angle, steering turned, etc) the crack holds itself together and it won't leak.

By the way I looked at the bag when it came out and didn't see any visible cracks. So the soapy water test might be hard to do.. not sure you'll actually see any leaks since they're so slow anyway. If you're going to remove the wheel to do the soapy water test, you're 1/3 of the way into the job of replacing the entire strut anyway...

Shellbmb

I'm not a huge DIY'er with vehicles. How much should it cost at a reputable indy shop to replace all 4 corners with the necessary hardware (bags, struts, shocks, etc.)?

We have a warranty until 100k so that's about up. And I doubt this would be covered or even found as sporadic as it is. I just don't want to own a money pit going forward. Car is still in good shape and it's paid for. Been on the fence about getting a new one. Guess I need to commit to keeping it for a while if I'm going to consider this repair.

BlownV8

A good warranty should cover the airstruts, at least, mine covered the parts and labor.

Shellbmb

I guess I meant they may not cover it if they can't find the problem. The previous poster was suggesting replacing all of them as a preventive measure and that would not be covered.

Blown, do you have an extended warranty? I think you are up to 170k, no?

Went out again and that same right front was slammed again. this time on a flat surface. So sure sounds like an issue.

drgeeforce

Consider Arnott, at $350 per, the basic DIYer can do it. They even have a video you can follow.
https://www.arnottindustries.com/par...18_pid146.html

bha

As Drgeeforce mentions, get the Arnott struts and have a shop install them.


Buy the entire front strut assembly ($400) and not just the airbag part ($350). You'll have more hassle and cost to disassemble and reassemble the strut than $50. It's way easier to unbolt the entire unit and swap it. someone here posted a huge problem they ran into with trying to disassemble also.. I think they ended up returning the bags and buying entire struts.


Rears are approx. $350 for the pair. So you're looking at approx. $1100 for all four corners.


I'd get all four parts and shop around at a few indy shops to see who can give you a good price to swap them. It's easy work.. for example, it took me longer to jack up the rear, put the truck on jackstands and remove the wheel than it did to pull out and swap the rear bag.


Fronts are more difficult. But not by a huge amount.


I have done all 4 corners and if I had to do it again, I could probably do it in 4 hours taking my time, 2 hours slightly rushed.


So see if you can find an indy that will charge you a few hours to swap them. I'd be suspicious of anyone quoting you 5+ hours because that means they haven't done it before, and think it's harder than it really is.

Shellbmb

Thanks for the links and the advice. Looking at the videos it doesn't look that hard. I'll give the stealer a chance to fix it if my warranty covers it. But good to know once this thing is out of warranty.

Been a rough month or so for the GL. Went in for routine maintenance and when i got back home there was an oil leak. Took it back and they said a centrifuge cap (??) was leaking. They fixed that. Now I get it home and the suspension is screwed up. I'm sure it's all coincidence.

MzP83

Just an FYI, the dealer has told me that struts are like brakes... no under warranty because it is considered normal wear and tear maintenance. Good luck with the warranty, maybe you will find something different. I just replaced all of my bags because both front sides were simultaneously leaking. Got the Arnott parts, all 4 struts replaced, and the compressor as well. The Arnott kit for all 4 plus compressor was only about $1400, and had a friend who works in an indy shop do the job for $400. I was quoted between $700-800 for other shops (I live in Las Vegas). Also, so you are aware, it's a good idea to get a balance and alignment done as well with this work.

BlownV8

What warranty do you have? MB replaced mine under warranty and my aftermarket warranty also replaced them.