HWH Active Air issue - left front cycling up and down while air leveled

[J&JD]

Maybe you got the defective front air bag that I sent back to Freightliner. It would have looked brand new. When I had my initial problem with the right front airing down I spent hours and paid for hours of checking for leaks all over the coach with both leak check solution and sniffers that detected leaks. A few small leaks were found but nothing that would allow such a quick drop of the right front. Finally I had the front bags changed even though there was no indication whatsoever of an air bag leak. As soon as I started driving the coach the new left front bag started leaking so badly that when I stopped I could literally watch the left front cycle up/down within a few seconds. Called Freightliner and they sent me a replacement and all has been perfect since with the spending of many $ for the bags and replacement labor. So the moral of this story is you can have an undectable airbag leak hiding behind the mountings.

 

[lostinfla]

Thanks, this one takes about a day to leak down, so I guess it's not your return.

 

[J&JD]

Pryor to changing the bags my right front leaked down after a few hours of being air leveled. HWH check everything and said all was good. On the way home I had the same problem (my home is 2k miles from HWH). I just lived with it until it got progressively worse. Changing the bags was the final fix even though I also changed the exhaust solenoid as did Neal.

 

[lostinfla]

I was thinking of removing the air line and making up a line, possibly with pressure gauge, to plug into the air bag fitting and using a compressor to inflate the bag to see if there's a problem there. Does this sound feasible?

 

[lostinfla]

OK, so I decided to do a little more checking myself, and I swear I can hear a small hiss up in the wheel well. (may be my tinnitus ) I did run it up to max and back down to min, but it's still slowly leaking down. I'm up to about 90% sure it's the bag and not the HWH valve. I went on Amazon and just ordered these parts. Going to make a short line with a Schrader valve and hook it straight to the bag. I'll then use a compressor to inflate the bag and check the pressure after a few hours. Should tell the tale. I'll keep ya'll posted.

Amazon.com

Amazon.com

Oh, and one of these.

Amazon.com

 

[Neal]

If you can see your manifold which I assume you can, spray it and see if it's leaking most likely on the muffler side (opposite back/solenoid) side. This is how HWH tests it, they actually remove the muffler and put some contraption in place of it that will show the leak.

 

[lostinfla]

If you can see your manifold which I assume you can, spray it and see if it's leaking most likely on the muffler side (opposite back/solenoid) side. This is how HWH tests it, they actually remove the muffler and put some contraption in place of it that will show the leak.

Yeah, I've been through that process with Joe on a former issue. They put a barbed fitting in the muffler hole and attach a hose which is then put in a jar of water to see if bubbles come out. I can easily get to both sides of my assembly to test later, but I'm still betting on the bag. I'll proceed to the HWH side if the bag passes my test.

 

[J&JD]

On my coach, HWH mounted Schrader valves to manually fill the bags. For the front bags mine are in the generator compartment near the horn. I have seen some mounted in the fuse compartment under the driver. Why can’t you use them to fill your bag(s) with a compressor? I did that all the way back to HWH when I had to shut down the system when it was acting weird.

 

[lostinfla]

I can do that, but that would not troubleshoot the bag by itself. That line goes through the HWH valve assembly and I believe it still relies on the solenoid seal. I checked the pressure at that fitting and it drops about 4 psi per hr. The coach is sitting in the back yard for the foreseeable future so I'm not in need of getting it road ready. I just want to make sure it is the bag before I take it to the local freightliner dealer for warranty replacement if necessary. I figure my labor is cheaper than their's and I don't want to pay for hours of diagnostic time when I can make sure myself and deal with Gaffney holding concrete evidence.

 

[lostinfla]

I did that all the way back to HWH when I had to shut down the system when it was acting weird.

How did you shut off the beeping alarm while driving with the system off? I tried turning it off on the way up to HWH this year and it drove me crazy till I turned it back on.

 

[lostinfla]

So, after a short bout with a cold, I got back to diagnosing the left front problem. I pulled the airline from the HWH block that goes directly to the air bag and installed a Schrader valve fitting to the end. I then pressurized it with 70 psi from my Vair compressor and monitored the pressure. It would drop about 1/2 pound every 2 min or so, so I decided to try spraying the top fitting again in hopes it wasn't the bag itself, and found the leak around the line entrance to the fitting. Removed the line and cut the end square and reinstalled. I am thrilled to say no leaks so far and the pressure is holding! As a tip, when checking for leaks, use Dawn power wash spray bottle. It really clings to the fittings and shows any leaks better than just soap and water will.

 

[Neal]

Great work inspector @lostinfla! Pictures would help if possible so we can see where you did what as I may still have my leak to chase as well. Not confirmed mine is fixed just yet.

 

[lostinfla]

I was going to take pics when I did it, but got involved and forgot. Here's a couple of the areas I worked on. The HWH bag line on the manifold is the lower left for the left front air bag. The next is the top of the air bag, and finally, the magic solution. (makes things nice and clean too) THIS TOOL makes things easy.