E550 front airmatic leaking down

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?

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.
Last edited by ccrobin; Feb 3, 2019 at 10:37 AM. Reason: spelling error





