Sherif Nayel

here is the situation
when I ever leave the car in the normal level for an hour or so its goes all the way down from the front side
but if I raise the car to the maximum level and switch off the engine I will come back after a week or so and it will NOT go down even one inch
any help

alx

some shocks will leak at one height, but not the other. so it could be a shock.

eric_in_sd

This has been discussed before. It's actually common behavior. The air bags develop leaks at the point the bag is bent and stressed, that is, folded at the bottom. So it will leak most at normal ride height. If you raise the vehicle, the area that was folded is straightened out, and will self seal.

I don't know why the same doesn't happen as the bag is folded under as the suspension goes down. but my truck had the same problem: If I parked it facing down a slight slope (my garage, facing out) it would leak. But parked in a driveway, facing uphill, it wouldn't leak.

Replace both front air springs. If one has gone, the other isn't far behind.

BlownV8

What he said.

gbigpapa

Simple trick to find out of bags are bad. Take an empty spray bottle and fill it with dish soap and water. Spray soapy water on airbags. If you see bubbles your bags are bad.

eric_in_sd

Great suggestion; only problem is if the leak is on the inboard side you might not readily see the bubbles.

gbigpapa

The bubbles will form and drip down. Just spray it all over so it runs down far side.

mbogohse

Gl 450 CDI - 2010 and I am having suspension trouble.

A little history, that has me confused somewhat. I shall be brief as possible.

A while ago I lost the front right and had both fronts replaced with Arnott and all was well.
A little while later the right rear was sagging, so both bags were replaced. After the replacement, the same side was still sagging and that went on for many months, until one night, very late at night, I could hear a hiss and it meant that the bag was leaking from the onset.

While I was contemplating how to go about this situation, coming home from the mall with the wife and kids, the vehicle refused to rise and malfunction light went on, I took it to mean the compressor stopped working or the vehicle was parked at an angle where the leak was exposed to the maximum and beyond the capability of the compressor. So we limped home 3 miles away. Next morning, like nothing has happened, it rose to the occasion.

The leaking bag was replaced with the previous we took off, the vehicle leveled like never before, beautiful.
On my way home from the shop, the right front strut goes out with a bang. Replaced the strut with the previous old OEM.
The vehicle leveled off beautifully. Everything was just perfect.

Next morning the front left is the only side that has sagged overnight, the other three are perked up as usual.
Once the vehicle is started, it levels off just the same as the other sides, the other sides do rise also a bit, enough for you to notice, not as much as the sag side. Park it for an hour or two and the front left will sag all the way where the fender meets the tire. The rest are at normal height.

Is there a possibility the leak from the rear bag was holding the compressor down and once that was sorted the compressor at full potential dealt with the weak front strut and since that strut has been replaced, the other side is now sagging.
Is there now a leak on the front left side now and perhaps is time to change that strut as well.
Could the valve body be a problem or could the compressor be working intermittently, perhaps not to its full capacity because it is now tired.

Also, as of now I have half and half Arnott and OEM, will that make a difference.
I will order new replacement struts and springs shortly.

Sometimes, I feel that there isn't enough air, it doesn't take the bumps too well. Lets say it isn't as comfortable as when the rear bag was changed, and before the right strut blew, it was majestic over the bumps, now you feel every little thing on the road.

I am still a newbie. I sure would appreciate some help from my peers.

Thank you so much

BlownV8

You have a 420 and not a 450.

chsu74

There is a valve block in between your air bags and air compressor. Air compressor is not strong enough to pump up the air suspension from complete flat after install. It is recommended that the car is jacked up close to normal height and then turn the car on to activate the air compressor.

I had my air compressor let go this summer. The valve block kept air in the air suspensions for one week until a replacement compressor was sent to me. Valve block is typically fairly robost but people have replaced them here.

I would check to see where the hissing is coming from. It may be a leaky bag or an improperly installed airbag if you are having issues with it. I also have heard bad airnott bags sent to customers too so you will have to do a bit of digging to find your problem.

Now if your air compressor have been working overtime, that part may be on its last legs..

mbogohse

Thank you for the insight, they may not have lowered the vehicle partially as you have said.
I found the hiss on the rear bag and I now believe it was faulty, but it was replaced with the bag that was taken off previously and the leveling is fine now, no hiss and no sagging.

The front strut is the issue.

I realize I have to get the a new pump asap.

Thank you

mbogohse

No Sir, its a 450GL, CDI - 2010.

I see and ride in it everyday.

Trust me it is, I have all the papers and have checked the Vin and specs with Mercedes themselves.

chsu74

It is entirely possible your front arnott struts were defective. Return it for a replacement. That is why they have lifetime warranty.

mbogohse

Thank you, I am in the process

BlownV8

Did you trade in your 420?

mbogohse

I do'ed yes

eric_in_sd

I had one Arnott strut go bad. They ship replacements free. Kind of sad that the "better" aftermarket parts aren't 100%, but ya gets what ya gets.

I don't follow the Arnott instructions to replace the hose end fittings. Only replace them if they are known to be a problem.

Definitely don't delay replacing a leaking bag. The pump isn't meant to run continuously. But in your case, I wouldn't replace the pump unless you know it suffered damage.

I don't know where anyone got the idea the pump isn't capable of raising from fully deflated. I never had a problem with that.

chsu74

This is what Arnott suggested in the install video. Maybe it is to not over stress the compressor?

eric_in_sd

Huh. Dunno. I remember that from the instructions. Yeah, I guess it makes sense to go easy on it, gradually lowering the vehicle so the pump can take breaks.

When I did the rear bags, I screwed up one of the fittings, and it blew out. The pump ran for a bit and then gave up, restarting after a few minutes. Probably a thermal protection.

Air pumps generally don't last forever, and the wear increases greatly with temperature. I considered putting a cooling fan on my portable tire inflator.