Airmatic

After working on my Airmatic, and reading EVERYTHING ever posted on this site (and on the web in general) about this, I can offer some advice.

This is NOT terribly complicated system. Don't be scared of it, and go slow and systematic in troubleshooting it. How does it work? Simple. The electricity is supplied to the pump via the (hopefully!) Hella relay (pass side fuse box - US config), the relay is the first one next to the three 40 amp fuses. First fuse next to the relay is a smog pump fuse (forget about it), and the middle one is #32 that protects the Airmatic circuit. Check that first. (and yank both pieces OUT BEFORE you start working on Airmatic!!)

Once the relay sends the juice to the pump, pump comes alive. The air comes in through the black hose (that has the filter in line!), and then the air is supplied to the valve (nothing misterious there, just a "crossover" valve that directs the air to the struts that need it, based on the input from the hight sensors - three sensors on the car - two front and one in the back). If the pump is working, but not sucking, either the filter is blocked (unlikely), or the hose is kinked, or obstructed.

If all connections of the white PVC lines on the valve (and the main that goes from the pump to the valve) are holding air, the car HAS TO rise. If it doesn't, there is a leak somewhere that is not easy to detect/see. Once the air is distributed by the valve to the struts, it goes to the top of the struts and inflates the air bags inside the struts. If the pump is working, and there is no air reaching the valve, the main PVC line is kinked, broken, cracked, or obstructed.

If the air (with correct pressure!) is reaching the valve, but it's not supplied to the struts,....the valve has a problem (electrical connections damaged, dirty, not connected, or valve itself going bad). If the valve is doing its job, and the struts are not being inflated,......struts have a LEAK (a big one!!).

Now,......when you removed the Airmatic pump, how did you lift the car, and more importantly, how did you LOWER it back down? If you read EVERYTHING about Airmatic, you will find out that overextending the strut can cause the leak on the strut under the bellows, and more importantly, once lowered down, you HAVE TO inflate the struts BEFORE the full weight of the car is on deflated struts!

When I replaced my pump, I used TWO jacks. One to lift the body, and one under the swingarm to lift the wheel without overextending the strut (I lifted only the pass side!). Pass side strut was never overextended, and after the replacement was done, I lowered the car until the wheel touched the ground (still on the jacks, without the full weight of the car on the wheel!!), and THEN I engaged the pump, and let it run for few minutes. I didn't have to, because my strut was not completely empty (valve prevents the complete loss of air), but I played it safe.

Bottom line,.....bellows never became detached, air never escaped, and after the pump was bolted and operated, I sprayed soapy water on all PVC connections, and detected no leaks.

So,.....read the Encyclopedia on the top, learn all components of the Airmatic system, and go slow. Once you learn how it all operates, and what each part of the system is supposed to do, you will find the fault, no doubt.

Good luck.

http://www.benzworld.org/forums/w220-s-class/1557414-2001-s430-airmatic-not-rising-please-3.html

Now, the rear suspension, in my opinion, almost never developes air leakes. The real problems come with the following.

1. Compressor failure or partial failure. 2. Valve block on top of compressor failure (very common) 3. Valve failure on rear suspension strut (often indicated by DAS) but wrongly. 4. Air leak on front suspension tops (for which there is a modification)

If it is 1 then new compressor. If it is 2 then new valve block If it is 3 then new strut (but uncommon) if it is 4 then do the modification

But however you look at this, if the garage does not have Star Diagnostics and a Mechanic who can interperate the values both in sensor voltage and other tests then dont waste your time and money.

http://www.benzworld.org/forums/w220-s-class/1329314-s-class-airmatic-woes-yes-again.html

If the air suspension on your Mercedes S Class has dropped on all 4 wheels and the diagnostic test is pointing towards an airmatic pump fault, you will most likely need to replace it. If the drop is limited to one side or wheel only, the fault will most likely be limited to that particular shock absorber air bellow unit. The airmatic pump on the W220 model is located under the driver side front wing splashguard. Remove the alloy wheel and remove the nuts and clips holding the splashguard in place.

http://www.nicedeals.co.uk/car/diy/8-mercedes/2509-mercedes-w220-s-class-airmatic-pump-replacement