Problem with air suspension 300 SEL - PeachParts Mercedes-Benz Forum

tosbt · #1 07-22-2003, 11:56 AM

Well the subject says it all, I have replaced all values and air bags. Holds well most of the time, but had it adjusted because it was slightly droped to the left. Picked it up yesterday was OK, and all the whole car is down today. Just a bit more dip on the drivers front. We have checked for air leaks, can find none, I'm thinking must be a bleading value in driver side or main. It must be letting off (venting) and then shutting down? Any ideas? Pictures of my car can be seen on previous post under "my 1972 mercedes" Thanks.

wbain5280 · #2 07-22-2003, 09:07 PM

You'll have to use soapy water to check all the connections at the various valves, air bellows, air tank, etc.

When you get bubbles, you'll know.

Regards

300SDog · #3 07-22-2003, 09:34 PM

Wait a minute.... isnt the 109 supposed to depressurize each time the car is shut down?

You might be misunderstanding the system - if you are dissapointed to see it flatten out unevenly when engine isnt running.

tosbt · #4 07-23-2003, 12:26 AM

I'm not sure if it depressurize or not. I thought it was suppose to hold for two months or so. For sure its not suppose to be uneven. The Soap thing I think is a for sure test, but I have done that and there are no leaks.

#5 07-23-2003, 12:52 AM

You should check the non-return(check) valve between the compressor and the reservoir. If it is faulty air pressure will be lost back into the compressor where it can not be contained.

wbain5280 · #6 07-23-2003, 10:08 AM

The airbags are supposed to be fully inflated at all times, except for repair. The leveling valves, two up front, one in the read attached to the middle of the sway bar, control the amount of air and will admit more if the load increases or release additional air if the load decreases. The excess air is returned to the control valve in the engine compartment, the one connected to the interior control knob.

If there is a leak, the car will settle on the stops after some period, determined by how much air leaks over time of course.

The leveling valves may also need to be refurbished. These are rather expensive new, if obtainable at all, or by exchange fron Neil Dubey(sp?).

Regards

tosbt · #7 07-23-2003, 03:07 PM

I have replaced the main valve and all leveling valves and all the air bags. It was my understanding that air was supposed to be held in the bags and was not supposed to drop for weeks or so if not in use.

Clunker · #8 07-23-2003, 03:45 PM

Have you adjusted the threaded bolts that level the car? There are 2 in the front and 1 in the rear. If the left front is shorter, the drivers side will pull down.

tosbt · #9 07-23-2003, 09:26 PM

Clunker, yes I think that is part of the problem. I can adjust the leveling arm up and that may push the drivers front up. But sooner of later the car will loose air and all four will hit boddom. Got to be some kind of bleed off, but I just don't see it. Nice ride when working right. Where are all the 6.3 guys.

Clunker · #10 07-24-2003, 12:44 AM

I don't know. I am a 4.5/3.0 air car man myself. Not to insult our intelligence, but there has got to be a leak you are missing. Did you try the valve on the air condensation tank? I know its a long shot, but all of my leaks have been easy to find. I don't think you have to bleed air suspensions: air bubbles in air? Maybe the car thinks you still have money! If I can get my shop manuals back from my brother, I'll do some research. Beautiful car by the way.

wbain5280 · #11 07-24-2003, 09:51 AM

Air bubles in soapy water, the factory recommended way.

Tosbt

You must check all air pipe connections and joints, esp the air tank. Make sure the condensate is drained from it by pushing up on the valve at the bottom of the tank. Watch out, it's very dirty. In the cold months, add Denatured alcohol to the frosted plastic container at the input to the air compressor.

There is also a schrader valve, like the ones for the tires, on the side of the tank. Make sure it doesn't leak as well.

Regards.

#12 07-24-2003, 09:58 PM

if you find the problem, pelase post the solution for it.
Thanks and good luck...
I wish I could help, but I just got my car and don't really know too much about it...

tosbt · #13 07-24-2003, 10:25 PM

Will do CB, have you looked into the crain electronic ignition? I changed mine and thus far the improvement is just great, smooth and seems to improvement at every level. Check it out under search.

Clunker · #14 07-25-2003, 12:07 AM

Thats right WBain5280! I've never looked at mine (though I've Used it too many times), but I guess it could leak or go bad. It is a ***** to look at as it is in the wheel well. But, like any other valve, it can go bad.

tosbt · #15 07-25-2003, 10:14 AM

I check the air tank with soapy water, no leak. Then I decided I would run a little test. Pulled the leaver out for the high position and drove the car for about 15 min. Put the leaver back to normal position and the car sat over night and has not leaked down as of yet. ????????? I guess I should let it sit for a few days, but the last time it went down on all four overnite and it was even.