Community Forums

conchrv · 03-21-2025, 06:30 AM

Country Coach 2001 Allure
350 Cummins engine
HWH ride leveling system 500 series
Dale Finigan Key West

My air dryer keeps purging every 45 seconds when driving. It does not purge when running (parked/stationary)
When driving on a good road, I monitor my two dash gauges for the braking system and they do not move at all. They stay the same at 120 psi (unless I do braking) My compressor does normal cycling at the proper regulator cut in/out (105-120 psi)

I am also monitoring my pressure of the initial tank that the “Pressure Protection Valve” feeds from.
As I am driving on a level road and not braking, I notice the pressure in this tank is going down to the 105psi and then raising back to 120 cut out when the compressor turns off again and purges.
(it just keeps doing this over a 45 sec period when only driving)

Testing I have done and parts I have replaced
1. I replace the dryer purge valve- did not solve the problem

2. I replaced my 20 yr old Air governor just in case- This did not solve the problem

3. I was going to replace the check valve in the air dryer, but instead purchased entire new dryer with new filter-
did not solve the issue

4. I checked for air leaks in park mode, ride mode, various level modes. I looked at both the braking and leveling component. I probable sprayed 3 bottles with no findings of leaks

5. I also checked the “air exhaust brake” solenoid and it seems to be ok. I make sure the dash switch was off when I did my road test.

6. I raised the RV all the way up, and all airbags and solenoids in the “HWH 6 pack” appear to be holding as it stays up for few days during the test (also I replaced the airbags 3 yrs ago). The airbags and system seem to be solid/holding

7. I believe the “check valves” between the air tanks are good, as I do not see any air back flows when I drain out the initial wet incoming tank. (the brake tanks old the air)

8. I believe the Compressors “unloadervalves”are not stuck or sticking, as it does not Purge when engine on and stationary.
Also the compressor appears to be turning on/off at the proper pressures of the new regulator (at 105 and 120)

9. I now thought it may be a bad Ride Height Valve, so I replaced all 3 of them since they are 20 yrs old. This did not solve the problem

10. I also ran the RV on the road with the HWH leveling controller off- fuse pulled, to see if it can help me in trouble shouting, but it I still keep getting the air compressor cycling and purging

Jzack · 03-21-2025, 07:23 AM

Have you checked/inspected with parking brake released and wheels chocked?

My first guess would be a brake chamber or brake system purge valve.

David 70 · 03-21-2025, 08:01 AM

It sounds like one of your parking brake chambers is leaking. If you are not familiar with them DO NOT mess with them. They have a huge spring in them that can be really bad for you.

conchrv · 03-21-2025, 08:04 AM

Thanks for reading and the feedback

I maybe in "left field on this", but i dont think its on the Braking side because my 2 tanks for braking do not loose air at all(untill i use hte brakes)

It appears it is only the incoming wet tank that the leveling air is tied to that is loosing air and i cant figure it out

I need to explore your idea on the Parking brake. Good point
Thanks again

d23haynes57 · 03-21-2025, 08:14 AM

Quote:

Originally Posted by conchrv

Thanks for reading and the feedback

I maybe in "left field on this", but i dont think its on the Braking side because my 2 tanks for braking do not loose air at all(untill i use hte brakes)

It appears it is only the incoming wet tank that the leveling air is tied to that is loosing air and i cant figure it out

I need to explore your idea on the Parking brake. Good point
Thanks again

While driving it is normal for the system to use air as the suspension will dump and refill the air bags while driving. Maybe that is what is happening.

David 70 · 03-21-2025, 08:14 AM

I guess I am not sure how the brake system is set up on yours. chock the wheels and release the brakes and listen for an air leak. I'm not sure if the parking brake release would come from the wet tank or not. It could be possible that the reed valves in the compressor are leaking back through the compressor. If they are then the check valves would keep the air from returning from the other two tanks. I've heard of it happening, but it is quite rare.

David 70 · 03-21-2025, 08:35 AM

You say you have the HWH leveling system. There could be a problem in there. See if you can contact AZPete on this forum and quiz him. If the air suspension is using that much air then there is a problem in the air bag system. Those air leveling valves have a delay built into them so they do not react immediately as the lever moves. That is so that as the vehicle bounces the air is not releasing and replenishing the air bags immediately.

Jzack · 03-21-2025, 08:36 AM

Quote:

Originally Posted by d23haynes57

While driving it is normal for the system to use air as the suspension will dump and refill the air bags while driving. Maybe that is what is happening.

Most leveler valves I'm familiar with have a built-in delay to prevent them from doing this.

It is true that if the leak is in the brake system you should see it on your gauges but I'm not familiar with the air leveling system in your coach that might play into this somehow and prevent you from seeing it on the gauges.

So if you haven't, definitely worth testing the braking system with the parking brake released.

azpete · 03-21-2025, 09:20 AM

i would check the electrical wiring for the chassis dump valves. seems strange to have air loss while going down the road and none sitting still. this may be a control box issue, or a 12 volt relay associated with the dump valve. 45 second intervals sounds like a relay failing and resetting.

Ray,IN · 03-22-2025, 06:54 PM

Quote:

Originally Posted by David 70

It sounds like one of your parking brake chambers is leaking. If you are not familiar with them DO NOT mess with them. They have a huge spring in them that can be really bad for you.

I agree. Air pressure holds the parking brake spring compressed when driving and parking brake off. If a parking brake diaphragm is leaking that badly one should be able to hear the air leak when next to the rear wheels.

**Lt Dan** · 03-22-2025, 08:08 PM

If it only happens when driving, then it's possible one or more of the ride height valves are leaking badly.

conchrv · 03-23-2025, 04:51 AM

good morning
i changed all 3 of the ride height valves a few weeks ago. i thought for sure this was it but no. My air goes down in the wet tank and purges (every 45 sec)
thanks for thoughts and feedback

Ray,IN · 03-24-2025, 07:39 PM

Does this happen when your parking brake knob is pulled out? What happens when your are sitting still with parking brake knob pushed in?

conchrv · 03-24-2025, 07:48 PM

hi Ray
I did that test this weekend. When parked and I released the brakes (knob pushed in)
I do not get the excessive draining from the wet tank and the purging. I don’t even see a Loss in Pressure from the braking tanks.
For some crazy reason, it’s only happening when I’m driving
thanks for your feedback