martinb

Greetings again MBWorld members:

I have a '09 GL450. I replaced the front airsprings and compressor in 2015. Recently, I have an unusual problem:

If I park the vehicle at regular (lowered) suspension height overnight, the rear right (and occasionally rear left) side will sag. If I raise the level before parking, the rear airsprings never sag. I have left it parked for over a week at the raised level - and it never sags. But when parking at the regular level, it will sag overnight.

It seems as though I have a leak only when it is parked at regular (lowered) ride height, but I never experience the problem if I raise the suspension just before parking the GL.

Has anybody ever experienced this or have any suggestions?

Martin

alx

yes. this is common. the puncture in the offending bag is shaped as such that at higher pressures seals itself.

martinb

alx:

Thank you for the quick reply. I was hoping to not hear "puncture" again, but it makes sense. When raised, the bag stretches vertically, so if the slit is also vertical I can understand that extra pressure is applied and helps seal the slit a little better.

I will be doing some spring conversion research now. I have grown weary of Airmatic for long term reliability.

Thank you again.

Martin

DennisG01

You mentioned you did the front, but do you know when the rear was done? Either way, although I have yet to do it, from what I understand the rear bags are super easy.

FYI, the reason the left side sometimes sags is (most likely) because some of the weight from the sagging right side is transferred to the left. But I believe they are pretty cheap to replace so maybe just do both and be good for quite a few years?

martinb

DennisG01:

The rear airsprings have never been changed. I am the second owner and have the complete dealer service history from the original owner. I just completed the 120000 mile oil change last week, so it seems like the rear airsprings served an above average lifespan.

I feel caution about sinking more money into maintaining the airmatic system. The cost of spring conversion for the rear appears to be less than or equal to the cost of the Arnott replacements I put on the front - based on a quick search.

I am aiming for long term reliability in my decision, even above cost. I know any pressurized pneumatic system will definitely develop a leak eventually. Failure of a coiled metal spring is very rare.

I will be checking prices and options for a coil spring conversion this week.

Martin

BlownV8

No way I would do the spring conversion on the GL. The airmatic parts are not very expensive and with Arnott you get a lifetime warranty.

rosenhauer

You can get the Arnott air springs from Amazon at a good price. Make sure you have a 10mm item end wrench, it's hard to get to the fitting with an adjustable wrench. Then it's a 1 to 2 hour job for both. Super easy.

martinb

blownv8/rosenhauer:

I have Arnott on both sides of the front suspension since 2015. So far, so good. But their lifetime warranty is a limited lifetime warranty. This is a marketing tactic. The fine print: they will replace a single set that fail to the original customer. You order them as you were ordering a new pair and they credit you the purchase after receiving your defective unit(s) back - once. When a hole develops in the replacement in the future, you are on the hook for purchasing another airspring. Their gamble is that you well sell the car before they fail and the limited lifetime warranty is nontransferable.

The two front Arnott airsprings were $1,000 with $200 refunded for core return. The most expensive conventional spring conversion kit I can find is $1700 for all 4, making it cheaper than the Arnott airspring replacement.

I understand those who want to use OEM parts - and more so those that do not want to alter the mechanical design of their Mercedes - but airmatic should be renamed to problematic. Any pneumatic system under pressure will develop a leak eventually - airsprings, hoses, compressor, valve block, or fittings. Springs do not suffer this weakness. After going through this problem already once, I do not wish to go through it repeatedly again. I plan to keep the vehicle well over 250,000.

Assuming these airbags last 100,000 miles, I can expect to change all four again before reaching 250,000 miles. Even if they are free, the trouble is not worth it. I would rather install conventional springs and be done with the weak link in the suspension forever.

Has anybody here completed a conventional spring conversion on their GL?

Martin

DennisG01

I have zero issues with changing things around and/or using non-OEM parts - as long as they are as good as, or better, than OEM.

Keep in mind that shocks/struts/springs do fail - they are not a "forever" item. Although, I do agree that springs will last much longer. But I'm not sure about shocks/struts lasting much longer.

The real issue I would have (granted, this is an opinion) about doing a switchover is... boy, the car sure does ride nice on air! For me, that trumps the other factors. Afterall, one of the reasons I bought this car was because of it's ride quality.

martinb

DennisG01:

I fully agree with changing parts out that meet or exceed OEM specifications. This is one of the reasons I am leaning toward Strutmaster's Eibach-based spring conversion - although I am not sure this justifies a $1000 price difference. I am trying to obtain specs on Suncore springs as a comparison now.

Back to the thread subject: I am trying to decide if there is a possibility that any other airmatic component could be responsible for my symptom. It is not logical that a faulty compressor or any of the hoses could reproduce my symptom. Is it possible the valve block could cause sagging when parked at regular ride height, but not when parked at the raised level?

Martin

eric_in_sd

It's a non transferable warranty. That's a standard tactic to, well, limit the warranty duration. I don't really have a problem with that; I can see that the company wouldn't want to be following a chain of ownership back to the original purchaser. Fixed period warranties usually are transferable.

I looked at the terms and saw nothing about a single replacement. My understanding is as long as you own the springs, they'll replace them if they fail.

So, careful about spreading misinformation. Fortunately I don't think too many read past all the italics.

For changing to coil springs, putting in gore-may stuff like Eibach is silly, almost as silly (in my opinion) as changing to coil springs at all. The exception I can think of is if you will be using the vehicle for extended long distance travel, where failure is not an option. Air springs are cool, but there's a reason serious off roaders don't use them. I've known other guys that have changed to coil springs; I didn't ask but I got the impression they did it out of frustration with the air suspension, not a demand for mission-critical reliability. Personally, I wouldn't let frustration be the driver.

Regarding your puzzle about leakage: The faults in the bags show up where they fold over. If it's raised, the leaking area, which was where the fold mostly was, is moved up and straightened out. This results in all kinds of anomalies, like the bag leaking when the car is pointed downhill on a driveway but not the other.

DennisG01

Martin, I think it's very possible that you could have a leak at one height setting, and not another - just like some others have mentioned. What's going on is that you have only a small leak, which will eventually get bigger and then it will likely leak at all height settings.

From reading these forums, I think that valve block issues can be diagnosed via Star/DAS/whatever it's called. HOWEVER, I can't imagine how a valve block can leak/not leak at different heights. If it was the valve block, one would think that it would leak all the time.

Try the old soapy-water trick on the bag, at different heights. That's how I found my occasional leak - in my case it the front/right, but same idea.

martinb

eric_in_sd:

View the warranty at the link below. It clearly states "Arnott will, at its sole option, repair or replace any components that fail in normal use" (Paragraph 2). The warranty continues "Arnott retains the exclusive right to repair or replace the product or offer a full refund of the purchase price at its sole discretion. Such remedy shall be your sole and exclusive remedy for any breach of warranty" (Paragraph 6). And finally, "Repairs have a 90-Day Warranty" (Paragraph 3).

http://www.arnottonline.com/arnottin...c_Warranty.pdf

I called them personally before making my purchase of the front airsprings to clear this up. I specifically asked them "If the new bags fail, I return them, and the replacement pair fail later, will I receive yet another pair?" The answer was "No." This is why it must be called a Limited Lifetime Warranty; it has limits. As stated above, at their discretion they can send you a repaired unit as your sole remedy (which is what most companies do) and then those come with a 90 day warranty. Worst yet - they can refund your money (on the first warranty claim) and you are on your own.

No company can stay in business continually sending you replacement parts - especially on pneumatic bags being continuously squeezed by a 2 ton truck. I researched this thoroughly before making the purchase. Their warranty, at least, was better than the OEM's.

To their credit, the Arnott bags on my front suspension are functioning great. I would expect them to last every bit as long as the originals: over 100,000.

Back to the thread subject: As you stated, I can understand how when the airspring is inflated and therefore straightened out, the leaking area leaks less. Based on this, I plan the bubble water test next.

Martin

martinb

DennisG01:

I agree. After studying all of the components, it makes sense that nothing can cause the airspring to hold air at the raised height, but not the lowered height, besides a vertical slit that closes up as the airspring extends when raised. I also agree that the valveblock would be an unlikely suspect because from what I understand each port is either open or closed. The position sensor simply tells the valve to open or close until it reaches the selected height.

Time for some soapy airbags this weekend.

Martin

eric_in_sd

You left out " or to the end of the original warranty, depending upon which is longer"

You've got a victim mentality. I can see being upset with the airbags' design - it's bad for the bags to fold like they do - but don't make stuff up.

Well, you're a bit of a hysteric ("personally"? as opposed to impersonally?), so I've got a feeling the guy on the other end of the phone said the warranty wouldn't apply to you personally.

Not providing a warranty on the replacement parts would be weird. They could send you junk parts and then not have to deal with you anymore.

I sent them an email asking for clarification. I'll post a followup when I get an answer.

eric_in_sd

Bright and early this Monday A.M. I got a reply:
"Please be advised that the part would be replaced under warranty even if previously replaced by Arnott."

martinb

DennisG01 and alx:

The right rear airspring has a very small slit. Almost unnoticeable if it were not for bubbles slowly appearing at the lowered level. After the airsprings were inflated to maximum height, the slow bubbling stopped. It looks like yet another airspring bladder problem!

eric_in_sd:

Read the warranty the way you want to. If you don't believe its wording, then believe the person on the phone. Good luck.

Martin

eric_in_sd

I'm sorry you are excitable and easily confused.

If you would like to put your mind at ease, I suggest calling Arnott again. You appear to have misunderstood when you were on the phone with them. Like I quoted to you this morning, Arnott says the warranty applies to replacement parts.

Prove me wrong, and I'll buy you a Coke. Otherwise, thank the people who helped you and go on your way.

Steve Bottin

Had the same issue. Ended up being the rear right air bag. Only sagged sometimes and never when elevated.

expl0rer

Same here, but mine was left rear. I tolerated it for a couple of months before replacing the bag yesterday.

eric_in_sd

Good 'ol stoner spit.

Usually the bags fail at the normal ride height fold. When you lift the suspension, the cracked part is pressed closed. However, it is easy to spot the leak then , as it will be about 3 inches above where the fold now is.

Avoid living with leaky air springs. They overwork the pump and also the dessicant, meaning water is being pushed into the valve block, where it gunks up the valves ... it's a big mess.

expl0rer

I would totally agree with you especially for those using the GL as a daily driver. Mine doesn't move too much from the driveway, except for the occasional run to the store or vet.

eric_in_sd

I'm still cleaning up the dog snot from the inside rear windows ... I'm leaving the stray hairs stuck to the carpet liner. I miss the dogs too much - daughters took 'em when they left the house.

P.S. I meant the leaky springs comment for general consumption. I know you know the score. It's one of those weird things, you don't realize the cascading problems that are under way.

expl0rer

Ours doesn't salivate over the windows. He demands them down so he can hang his head out and observe. As the official navigator, he's got to know what's up around us all the time. And just in case I forgot to roll down the window just when it should have been, I'm the recipient of the stinky eye. Head down, eyes straight at you. I swear he learned that look from coyotes or wolves or something. Aptly nicknamed "The King of Ambrose"! He's a sensitive soul. 🙂

I don't bother with the pet hair anymore. We wear it proudly. It's a fashion statement most don't get lol. You should get another dog, it fixes everything soul related, just like duct tape in the physical world.

About the leaky spring replacement, I responded just in case someone who drove daily came along and saw this thread and thought it would be OK to procrastinate the replacement like I did. I don't want to teach others my bad habits. I'd rather keep them to myself. And totally didn't take it personally. I'm not as sensitive as the 4 legged king.😁

eric_in_sd

lololol you're all right,, my friend

Wish I'd taken a picture of it. There was a full size golden doodle riding shotgun in a Subaru here. I pulled up next, on the freeway, and he and I exchanged long loving stares till the exit came up.