[RussWhite]

Hi Gurus,

I am right in the midst of getting ready to head south for the winter.  Loads of stuff yet to accomplish today and early departure towing car tomorrow.   So maybe the is why I can't seem to think well enough to figure this out.

Asking for your insight into how the following symptoms might relate to a component failure.  I will followup when someone gets it right or I figure it out.  I plan to travel with the problem as I don't think it is dangerous and I have a work around for the one scenario that would get me in trouble ( going to travel mode after fulling raising the coach to get over the tracks).   Below is just a cut and paste from my notes and a picture of my HWH control panel so you will know which buttons I am referring to.

11/11/16
 
I heard an air leak when the coach was in travel mode.  Sounds to be coming from the front HCV.
 
I force lowered the coach well below travel height and put it back in travel mode – brake on, e-brake off, and in D, then back to N, E-brake on, brake off.
 
With engine running there was no leak  and I watched the coach come to ride height, maybe a hit too high, and then the air started to leak at a rate I could hear again.
 
The engine air compressor keeps up with the leak easily, even at idle.
 
Looking at the air system diagram I think it’s not obvious to me right now.
 
trying another test
Raised front to above ride height.
No air leaking
Put in travel mode
Air exhausting/leaking but the front does NOT go down to ride height
Took out of travel mode with AIR button and air leak stopped
Coach sitting too high.
Used down arrow to drop well below ride height.
Put back in travel mode
Came to ride height, and then the air leak started
Settled at about the correct height.
Pressing AIR stops the leak.
 
 
 
This will be a problem after crossing the railroad tracks as I will be too high ( due to manual raise to get over ) and it will not go down properly when I return to travel mode.  I will need to lower manually soon after crossing.  

[Fulltiming]

Take a good look at the HCV, I suspect that it has a crack in the plastic housing. I had one that did the same thing. Newell spent an hour or so tracking down air leaks and pronounced it good to go. It was hold air fine. I parked it outside on one of their spaces, leveled it and it started leaking air like crazy. Tommy quickly found the culprit. The left rear HCV had a crack in the housing. It only occurred when the HCV was raised above the normal ride height. We pulled it back in the shop and replaced they replaced the HCV and all was good again. At normal ride height it wasn't leaking, raise that side and you could hear the leak.

[Fulltiming]

Rereading your post there is one MAJOR difference between the leak I had and yours. You state that in travel mode the front did not come down to ride height but did in level mode. Again, that points to a potential HCV problem just may not be the crack mine had. As I recall, the HCV has an exhaust air port on the bottom of the HCV itself.

[Richard]

In a weird coincidence, I spent all day working on my front HCV. And I learned a WHOLE lot that may help you when you work on this.

I don't readily know the answer to your issue, but let me talk about the things I learned today.

When I first saw the setup, I was certain that someone had done a hack job on installation of the HCV. The reaction arm was way too short in my opinon. I thought that would make the valve too sensitive to up and down movement and waste air.

I was wrong. Newell mounts the lower part of the vertical rod to the sway bar in my case. The valve is hard mounted to an arm welded to the frame. So the movement is actually the rotation of the sway bar. Unless the mount on the sway bar extended all the way to the axle center line, which it does not, the movement is actually much less than the movement between the tires and the frame.

So the way this is compensated is the reaction arm is shortened.

All of that to tell you this. The length of the reaction arm has a tremendous impact on the dead zone. The dead zone being the hysteresis in the vlalve action. If I raised the coach and then put in travel it settles to one ride height. If I lower the coach and let it raise it settles to a lower height. Drum roll. If the reaction arm was five inches there was 7 inches difference between the two heights. If the reaction are were shortened to 3 inches the difference in the two heights was about 2.5 inches. I shortened the reaction arm to about 2 inches and the difference heights was right at 3/4 inch. So, if you get to fiddling with this valve be aware of this situation.

It gets even better. With the reaction arm so short any movement of the up and down rod is exaggerated. 1/4 inch of adjustment in the up and down rod made 1 1/4 inch difference in ride height. Be aware that very small adjustments make a huge difference in ride height. This is completely different than at the rear where it is virtually linear, move the adjustment rod the amount you want to change the ride height.

To your particular problem. I suspect either a problem with the internals of the HCV or a leak between the HCV and the six pack.

A quick diagnostic may help. If you lowered the coach below ride height and put it in level, do you still hear air? If you do, then you have a leak between the HCV and the six pack. Here's why. The HCV always has supply pressure, and if the coach is low the valve is actually trying to raise it, but since the output goes to the six pack travel solenoids, that air path is effectively blocked at the six pack, but it would be pressurized.

You stated that that if you raise the coach and turn on Leveling that the air hiss stops. That tells you the air line into the HCV is not leaking, since the air line into the HCV is always pressurized whether you are in travel or level.

The valve could be defective in that it is trying to raise and exhaust air at the same time. Having taken an HCV valve apart this morning, I can see two things that would cause that. Debris, or broken internal parts of course. Also, if you have the valve that Michael pictured, if you remove the rubber boot on the bottom, then the felt filter, you will see a white cylinder with a screw in the middle. Turning the screw clockwise increase the dead band in the valve, or in other words a half turn inward may get you out of the raise and lower simultaneously mode until you get a new valve.

I can't say without really observing your coach, that your concern about it not coming back to correct ride height is part of the problem. Or its that issue I talked about earlier where the coach will reach different ride heights depending on whether is settles down to ride height or it raises to ride height.

Gee I hope that makes sense and helps.

You have my number.