GL Class (X164) 2007-2012: GL320CDI, GL420CDI, GL450, GL550

Slow leak in rear Airmatic 2009 GL550

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Old 12-30-2016, 09:42 PM
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2010 S550; 2009 GL550
Slow leak in rear Airmatic 2009 GL550

So we have replaced both front airmatic shocks PLUS the compressor. Now we are getting sporadic leak-off in both back shocks, sometimes both leak off, other times just left rear leaks off. Sometimes they will leak-off very low but leaving about an inch of clearance above the tire, other times 2-3 inches vs the normal 4-5" clearance. They will some times go weeks without the issue. Any suggestions on why they are acting this way? I am thinking the airmatic shocks are slowly failing, and as eluded to in other discussions could put an undue stress on the compressor. But why would both go bad simultaneously? The fronts went months apart. Note also that the leak off never occurs when vehicle is in use, only after stopping for periods of time, sometimes 2-3 days other times an hour.

Thanks all.
Old 12-31-2016, 01:09 PM
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Originally Posted by timwalker69
So we have replaced both front airmatic shocks PLUS the compressor. Now we are getting sporadic leak-off in both back shocks, sometimes both leak off,...
This has been discussed endlessly here. The main reason I'm repeating is to point out that the rear shocks are physically separate from the air springs, which are like balloons. In the front, the air bags are like a donut surrounding the shock.

The bags have a modest lifetime. Just replace them. Aftermarket (e.g. Arnott) don't seem to be much more reliable, but they are cheaper than OEM and have a lifetime no-hassle guarantee.

Replace the rear bags before they over-stress your new compressor. They're even easier to replace than the front.

Also, I recommend not replacing the line fittings despite Arnott's instructions to do so. It saves time, and replacing them adds to the risk of things going wrong during installation.
Old 01-06-2017, 09:11 PM
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Thanks Eric, I watched a video link from Arnott and it even looks like a caveman could do it. In case I cant find my inner caveman, what would you guess that a dealer would charge per side? The Arnotts are $180. My guess is OEM are probably $300. It only took the guy on the video maybe 10 mins total with part of that disconnecting compressor fuse, raising the vehicle, and removing the tire.

What are the chances the shocks need replacing at the same time in your opinion? Thanks again.
Old 01-06-2017, 10:34 PM
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_everything_ that needs to be said about airmatic has been said. please use the search function for the forum...
Old 01-07-2017, 04:43 PM
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Originally Posted by timwalker69
What are the chances the shocks need replacing at the same time in your opinion? Thanks again.
Ditto what alx said: Search is your friend. It'd be great if the forum had a button you could click to quip DAFS.

Rear shocks are almost completely separate from the air spring. Shocks last ~80k miles. It would hardly hurt to change them earlier, because they progressively degenerate.

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