I've had an H3 for years, just bought an H2 a couple days ago. 2006 80k miles, parked in garage on flat concrete and I noticed the rear has dropped. Anyone else experiencing this and is this normal? Air suspension bag leaking? There are no service indicators or messages coming up. Thanks for any info on this!

 

My guess is you have a leak somewhere in the air suspension. Spray soapy water over the bags, lines & fittings to see where its "bubbling" / leaking from. If you are losing that much overnight it should be easy to find.
Your air springs may be the culprit if they are original... they can get slight cracks in the rubber after years of movement,
this is the air spring part number if thats where fault is found - 15938306 (replace both if one is bad the other is probably not far behind).
Install is pretty easy - if you have a garage do, shouldnt be more than 1.5 hours labor - they both can easily be swapped in that time.
If you do need the air springs, they can be found relatively inexpensive - OEM usually around $150 +/- Generic $75 -
for example amazon-

Amazon

Amazon

I went with OEM when I did mine....
There are a bunch of how to change posts if you look on this site and want to do yourself,,,

 

Do both sides drop equally?

Both air-bags leaking at the same rate is unlikely, but you could be lucky if this is case. Of course try the soapy water.

If not it could be the inlet valve assembly itself. (search for "Air Suspension Inlet Valve" for the youtube video)

If you disconnect any pipes DO NOT GREASE them,just clean.

 

I'd also suggest that if possible, whenever you to disconnect any tube, first use some compressed air to blow any particles away. I've had dirt fall into a fitting before on removing a tube...

 

ok great thanks for the info. We have new bilstein shocks on the rear, we will try the soapy water. I've read other people have the same thing happen and it levels out once turned on and some say it's normal?

 

yes both sides equally

 

Not normal! You have a major leak and/or height control sensor easy to find/repair.

 

Yep, not normal. Maybe it will sag down some if left for a couple of months or more without being started but not within weeks. When I replaced mine a few months back I had it in my shop for about 3 months while I was also doing other work on it. Replaced the bags, and over about a week it would sag back down. So I sprayed soapy water and found that the tube was leaking at the top of one of the bags. You can remove the real wheel house linings and really see the top of each very well and with careful looking with a flash light from various gaps and angles you can also see most all of the fittings on the compressor as well without taking it down. Anyways I removed the tube from the one that was bubbling with the soap, cleaned the end of the tube with a soft damp cloth, stuck a cotton swap in the fitting to make sure nothing was in there like dirt or something maybe stuck on the o-ring. Put it back in, aired up, and it sat there for over a month without sagging down one bit while I reinstalled the headliner and other stuff.

 

MixManSC you could be on to something here. After re-installing my AS Unit (worked on brake lines) the rear-end sagged 50% ish overnight, so I re-cleaned all the tubes + ports involved.

Although reducing the drop, it didn't eliminate it, the strange thing, over the next few weeks things recovered back to normal, almost as if the fittings were "bedding in"

Could it be that deep contamination around the pipe/port connections is acting as a barrier? Having worked with industrial pneumatics, I understand the importance of cleanliness, so maybe the 2nd time I cleaned I broke down the barrier a bit more i.e. I didn't go deep enough the 1st time?

Perhaps the guidline should be "Before reconnecting, thouroughly clean and degrease the air-pipe and ports as much as possible" ?

I also know never to lubricate the air lines, they'll fly out with the slightest pressure.

 

On my past H2's I took to the Chevy dealership on two of my past ones, I had some leak down overnight. Both times after replacing bags... I do not know if they tried what oceanbrave & mixman tried or not - however on both of these they ordered a new air line to replace the one leaking... Unknown if they tried cleaning or maybe the end got the slightest of scarring or deformed upon R&R of the bag.... anyways in both instances the new airline resolved it - you can still order the airlines through GM (I havent checked lately but imagine they still are). On my current 2006 I replaced the bags because of severe leak down over days.. I had a very slight leak that would sag the rear if left for a week (noticed after vacation) fairly soon after I replaced the bags... I havent noticed any noticeable sag since that happened months back, however I havent gone a week without starting it. It may have resolved itself as you mention oceanbrave.. I may try to leave it for a few days & measure out of curiosity if it still has the slightest of leaking.. maybe measure and leave it for a few days.
Visually I have not noticed any sag since the time after vacation..