October 31

2008 Mercedes GL320 Air Suspension Repairs

Mercedes, Podcast


Mark: Hi, it's Mark from Top Local here with Bernie Pawlik. Pawlik Automotive in Vancouver. Thirty eight years repairing and maintaining cars in Vancouver. Twenty one time, only 21 time winners of Best Auto Repair in Vancouver as voted by their customers. And we're talking cars. How are you doing today, Bernie?

Bernie: Doing very well.

Mark: 2008 Mercedes GL320 had some problem with the air suspension. What was going on with this vehicle?

Bernie: Yeah, so the vehicle came to our shop not sitting properly. One corner of the vehicle was leaning down too low. Yeah, so that's basically the client's complaint. The suspension system just wasn't levelling itself out properly.

Mark: So how do you test to find out the cause of this?

Bernie: Well, first of course, a visual inspection. Then there's a couple of buttons on the dash you can press to raise and lower the vehicle. That wasn't working. Next step, a scan tool. A good quality diagnostic scan tool. We found a couple of codes in the system with low system pressure, and then we performed some diagnostic tests. The scan tool we have is awesome. You can run a number of tests where you can set the level of each air spring. You can test the pressures in different parts of the system. And what we found is basically the pressure was very low, and nothing we did would would operate. As the test went by we found the compressor basically was not operative and it basically died.

Mark: So, is the compressor the only part that you replaced?

Bernie: No, we also replaced the ... There's a solenoid valve pack located right above the compressor. We'll get into some pictures in a minute, but that's also a common failure item on this vehicle. It was original, like the compressor was, and so it was a good time to replace that piece. And not a lot of extra labor involved with the compressor out and it just made a lot of sense.

It's good to do these things. Often when parts are located nearby each other, there are sort of common failure items to replace them in partnership. It makes for the repair bill a little higher, but then the customer's not going to be coming back in a month or two or six months or maybe even a year going, "Oh, this side's not opening or closing. This spring's sitting too low," because this part's failed now. Then you've got to pull everything apart again and change the other piece. So, it kind of makes for a more thorough, satisfying repair.

Mark: And adds longevity. So did you find any other issues when performing these repairs?

Bernie: Yeah, we did. And what I'll do, let's just get into a quick picture share and then I'll talk about some other issues.

2008 Mercedes GL320 Air Suspension Repairs
2008 Mercedes GL320 Air Suspension Repairs
2008 Mercedes GL320 Air Suspension Repairs
2008 Mercedes GL320 Air Suspension Repairs
2008 Mercedes GL320 Air Suspension Repairs

There's our full size GL320. This is a diesel. Again, yeah the full size, the ML's similar but a shorter, slightly smaller version. So this is a Mercedes full size SUV.

And, other pictures. So let's have a look. This is the compressor. This is with the right fender liner removed, so the wheel would be sitting right here. There's a big plastic fender liner comes out, and there's the air suspension compressor located right in this area here. The a solenoid valve pack that I mentioned is located right up here. We'll just get into a little more of a closeup picture of this piece.

This is the compressor, sort of viewed side on. This is the air inlet hose where the air is sucked into the compressor. So the red arrow indicates the compressor unit, which it goes back in, it's a fairly large piece, goes back in a little ways. And then the a solenoid valve pack sits up here. Basically, this is the main airline from the compressor and then it has five other lines that go off to various other areas on the vehicle. Four to the air springs, and one goes elsewhere, which is probably a vent line or possibly an air reservoir. Anyways, six lines on that piece.

Now what else have we got here? Yeah, so what else did we find? This is the main power connector to the compressor. This runs the compressor motor, and as you can see, it looks a little ugly. When I removed this, there's two electrical connectors. One of them which operates a solenoid, popped off right away. This one here required a bit of a hammer to bang it off and it was pretty evident as to why the connector was stuck. It basically had overheated in this plastic and melted. And why it overheated, this adds another issue that needed to be repaired.

Fortunately, Mercedes has repair wires and a nice connector plug in stock, so we can actually take these wires, cut them, solder them, put proper heat shrink covering on it, and it's got proper weather packs and a nice connector and everything fits well, and it's going to ensure the right connection to the compressor. So, that was the other additional repair we found, that this wiring plug had overheated.

Mark: So once you replace all this stuff, is it just turn the car on and everything works, or is there something else that you need to do?

Bernie: Well, you'd think it would because it's all computerized and it has ride height sensors and pressure sensors, and it would go, "Okay, there's not enough pressure in the system. Let's pump that up and let's raise and lower the height of the vehicle," but it doesn't seem to work that way. It seems to require a bit of finessing to get it going. So I had to basically manually power up the compressor to build up the pressure, and then from there, on our scan tool there's some height adjustments you can do to adjust the height level of the vehicle. And so that's a bit of an involved procedure, but once we did that then the vehicle sat properly and the whole system came back to life.

Mark: So, why did this compress your die? Is it just old age? This is an 11 year old vehicle.

Bernie: Well, old age is part of it. They only have a limited life span, and 11 years is a pretty good run for one of these parts. But the other thing, a bit of history on this vehicle, a couple of months ago the owner had some issues with the suspension system and we found the two front air struts were leaking air. The right rear also had a leak or there was something going on with the right rear. I believe the left rear had been previously replaced.

So we replaced three of the four air struts. So that, of course, taxes the system. This system runs very hot, as you can see, those wires that were melted. There's a lot of current. This system is fused with a 40 amp fuse, which is pretty large. And in my process of filling the air suspension compressor I put in a test relay, which basically bypasses the system and allows me just to power up the compressor.

And after running it for about three minutes, I pulled the relay out and it was so hot I could barely touch the connector pins. So there's a lot of heat generated, a lot of current flow, and so if you run the compressor a little too long it'll shorten the lifespan for sure.

So had these air struts not leaked, chances are the compressor may have lasted longer. But this is also one of the higher failure items on any air suspension system. The compressor, it works hard. It's not always on, but several times a day or during a drive it'll be on to adjust the suspension system.

Mark: So just so we're clear about it, when the air is leaking out of the air struts, the compressor has to run to try and replace that air that's leaking out so it's running a lot more.

Bernie: Exactly. Exactly. And what'll happen too is, there are timers in different vehicles, they have timers on the compressor or temperature sensors on some of them. So, if the temperature exceeds a certain amount in the compressor or runs for a certain amount of time, it'll just time it out. And this is when you start noticing how the car is not ... It won't level out properly because the compressor will run for a while, then it just shuts off and then it has to cool down and it'll run for a while longer. So there are built in features to prevent them from overheating and burning out, because that will happen if you have a bad leak. It'll just keep running and it'd fry the compressor, and who knows what other wiring issues will happen, too?

Mark: So, is there anything that an owner of an air suspension vehicle can do to lengthen the life of the compressor?

Bernie: Well there isn't really, other than if you happen to notice the vehicle's sitting funny, certainly get it diagnosed and fixed right away because that'll probably be causing the compressor to run too frequently. And so, the faster you can repair it, the longer your life of your compressor will be. So, that would really be the only thing I'd advise. Other than that, I mean, it's a self contained sealed system. There's no filters to change or anything else to do it. It really kind of runs itself, and the components will last as long as they do.

10 to 15 years is kind of what you're going to get out of an air suspension spring, so if you own an older one you can kind of count on they're all going to need to be replaced if it's 10 years old or older. They're all living on borrowed time. They are expensive, but an air suspension is awesome because you do have control over the height of the vehicle. You can raise and lower it in most cases for better ground clearance, or drop it down for better handling. If you pack it full of people and cargo, the car rides nice. But it all does come at a price.

Mark: So just to go back into this leak, how would you know that there's a leak in your air suspension? You come out and the car's sitting funny, or it's lowered?

Bernie: Exactly. You'll come out in the car sitting funny. That's the kind of thing where you come out in the morning, maybe you park your car at night, you come out in the morning and maybe the left front corner of the car is sitting too low or the right rear, or whatever it is. One corner of the car will be sitting too low, or you might-

Mark: Or all of them.

Bernie: Or all of them, yeah. If they're all down, that's an issue, too. You know, it's interesting. We actually have another Mercedes of this exact type in the shop right now, and the owner complained some issue with the air suspension. We looked at, it seemed to be fine. It needed some other work, so we did some other work on the vehicle. Brakes and a couple of other services. Put the vehicle back on the ground, drove out and the front air springs junk sunk. So they had tiny little leaks that weren't really apparent, but then after looking at it, okay the left front struts leaking. Of course now both of the front ones dive. So it needs air struts on that vehicle, too.

So if you notice anything that's sitting off, right away, that's the time to get it in for repairs. Unfortunately you go, "Oh yeah, it's going to cost money." It will, but it's better to do it sooner than later.

Mark: Yeah. It's going to cost money right away, but if you leave it, it's going to cost a heck of a lot more because now you're replacing the compressor.

Bernie: Yeah, exactly. And the thing is, it may be that inevitably the compressor's going to go anyway because if it's original, it's never been replaced, and the vehicle's again, 10, 12 years old, the compressor's probably not got a lot of life left in it anyways. But fix it as fast as you can. That's the key with any vehicle. You fix what's broken, or any noticeable issue, fix that first and that'll save you money in the long term.

Mark: So there you go. If you're looking for service for your Mercedes or air suspension vehicle in Vancouver, the guys to see are Pawlik Automotive. You can reach them at (604) 327-7112 to book. You have to call and book ahead, they're always busy. The website, pawlikautomotive.com. 640 plus articles and videos on there for your viewing pleasure. Dig in. There's tons of information on repairs and maintenance of all makes and models of cars. How to prepare your car for winter, et cetera. Of course, Pawlik Auto Repair is our YouTube channel where we have, again, quite a few hundred videos talking about all makes and models of cars. Thanks so much for listening to the podcast and watching. We appreciate it. Thanks, Bernie.

Bernie: Thanks, Mark. Thanks for watching.

About the author 

Bernie Pawlik

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