georgiabenz

I have a 2007 E550 with 101,000 miles. Owned it for 12 weeks. Shortly after purchase I would notice passenger side front wheel a little low, but I got no warnings or codes and everything was fine. A couple of weeks after that I started getting the "Vehicle Raising" warning. Then everything ran fine. Now, both front wheels are fully deflated each morning and I get the "Vehicle Raising" warning every time I let it sit for three hours or more.

I did a quick check on the valve block by removing the line to the compressor at the valve block. I used soapy water and identified that the valve block was leaking back through that port between the compressor and valve block. I replaced the valve block with a used one, but I get the same thing, the front wheels are dropped after a few hours. Also, after 10 minutes of driving or so I can hear the wheel tapping against the fender well but I no longer get the :Vehicle too low" warning and there are no error codes even when reading with a professional (but not Star) scanner. I pull over, hit the Vehicle Rise button, the pump comes on and it raises both sides and is okay.

All the while the back wheels are fine, no leak down at all. Sometimes it appears that the back wheels are a little high, but my scanner has them anywhere between -5 mm to +10 mm.
The front shocks when fully inflated still show -12 mm and -14 mm.

What would make just the front shocks to bleed down if it is not the valve block?

Plutoe

The airmatic system is a very complicated electropnumatic system and you need the special diagnostic equipment to localize the problem.
Using the ole FUYA approach will not solve the problem. You have a leak in the system. Take to a place that understands MB systems and get it fixed it aint a DIY

georgiabenz

Thanks, I wasn't trying to be a hero, just wanted to know if there were some things to check before taking it elsewhere. It just seemed strange that both front struts would bleed down at the same rate.

ccrobin

I had this issue with my 2004 E350, but on the rear. Sporadically I would come out and find the back end of the car sitting very low. Once I started the car it would fill back up. Don't ignore it for long though, a small leak will become a big leak. If you lose pressure while away from home you'll be stranded and need to have the vehicle towed. The air pump can only keep up with so much of a leak. Also, the air pump is not designed to run constant so delay too long and you'll burn that out as well.

For me it turned out it was the air shocks - one had a small leak.Not sure why it affected both sides but it did. MB wanted about $3K to do the job (at least for the rears as they claim they need to remove the subframe to get at them). I purchased a pair of new Arnott air shocks for about $500. The entire job took me only an hour - no subframe removal necessary. The trick was to use a paper clip to get all the air out of the old shocks (insert it into where the air line hooks to the shock - there is a schraeder type valve like you would find on your tires). Once fully deflated they compress enough to get them out and the new ones in.

There are some good guides on the forums if you decide to tackle it. Your car is at the age and mileage my money would be on the air shocks. It's rare to get leaks in other parts of the system. Also, if you decide to do them, you probably need to replace the pair otherwise you will get airmatic errors.