HWH Air Bag Leveling Leak

[Pat Long]

I have the HWH air and hydraulic on my coach and am now experiencing on the drivers side rear a slow air leak.  Once I level the coach overnight it will loose air and only affects the drivers side rear.  I have been under the coach for the last two days listening with my ultrasonic listening tool with ear phones, very sensitive tool, magnifies a small leak into a roaring jet sound.  Even using a soapy water spray bottle, I still can't find the leak.  Have checked ride height valves, HWH 6 pack, check valves, air tank fittings, air line runs, and even all rear air bags.  Even loose all air 120 lbs overnight

If I am not mistaken once the air goes through the HWH 6 pack to level the coach it can't reverse flow and is held inlace until dumped.  It this correct?  I believe that others here have experienced the same thing and hope someone can point me in the right direction.   Had the coach just a little over a year and still finding things to learn about the systems it has. 

[Mike Shumack]

I have the same issue - although not leaking as fast as yours.

The air in the leveling system is "supposed" to stay isolated from the main air system by a one-way check valve at the air tank. So air can flow into the HWH leveling system but a leak in the "coach (main system) side", should not let HWH air system pressure drop even if main air pressure drops to 0. However, it is not uncommon for the one-way check valve to leak (internal leak).

A leak as large as yours, should show up with the soapy-water spray bottle if it is external.

Here are two drawings that "help me" understand how the system works. Your system may be different but probably not by much. Note that the Air Bag line is connected to the Raise, Lower, and Travel solenoids. If any of those are not closing (seating) fully air can leak past internally.

[Mike Shumack]

 I think you would have to have two faults for the HWH system to drain the main air system; a leaking one-way check valve and a leaking Lower or Travel solenoid allowing HWH air to leak out the Exh port of either of those solenoids.

Have you sprayed around the Treadle Valve (foot pedal) and Relief Valve (connects to rear brake chambers)?

[Pat Long]

Mike,    Spoke to Randy, a Tech at HWH today and he said what I was thinking about the system operation is correct.   Once the air flows through the leveling valve it will be a sealed system, no other leak behind the leveling valve will effect the air in the bag.   The only way you will loose air is if a seal is bad in that valve or the airbag involved has a leak in the feed line or the bag itself.  And Yes one more I forgot to mention is during the manufacturing process in machining the block are 2 ports next to the mounting bolts at the end of the block.   The factory will install 2 allen plugs to block those 2 ports after machining, sometimes they will leak also.

[Eric Palmer]

I'm glad I came across this thread. I have a 1998 Patriot Brandywine. The coach airbags settle overnight as well and I wasn't sure if that was normal. Now I know to look for a leak. Also, while driving my air pressure gauge fluctuates a lot. Not when sitting still idling, but while driving and the coach is bouncing around a bit. It will go from 125psi to 80psi in 2-3mins (no brake actuation) and then the governor kicks in and brings it back up. Is this normal? If not would it be connected to the issue of my airbags having a leak? Thanks for any advice!
Eric

[Steve Huber]

Eric,
Not normal. Suspect a leak.
Steve

[Joel Ashley]

I agree with Steve here, Eric.  Normal driving with bag micro-adjustments shouldn’t result in that rate of dryer cycling.  You need to have a reputable facility evaluate your air system.

Joel

[Eric Palmer]

Thanks. I'll have my system checked out!

[Lee Welbanks]

Mike,    Spoke to Randy, a Tech at HWH today and he said what I was thinking about the system operation is correct.   Once the air flows through the leveling valve it will be a sealed system, no other leak behind the leveling valve will effect the air in the bag.   The only way you will loose air is if a seal is bad in that valve or the airbag involved has a leak in the feed line or the bag itself.  And Yes one more I forgot to mention is during the manufacturing process in machining the block are 2 ports next to the mounting bolts at the end of the block.   The factory will install 2 allen plugs to block those 2 ports after machining, sometimes they will leak also.

Pat, I don't know what your manifold looks like, on my 06 PT I have six solenoid valves and two pressure switches. I have had to overhaul three of the pressure switches that were leaking, they are very hard to tell that they are leaking, usually leak out of the set screw hole. Have to soak the heck out of them and cover the hole with your finger to see bubbles. Also have had a leak with one of the allen head plugs. Of course all this is so easy to get at and see up under the coach.
If you park your coach and leave the system in travel mode does it still leak down, if left in travel mode it should isolate the rest of the system. With yours leaking down overnight I would think you have more than one leak.