Sinking Coach

I have a 1996 Royale Conversion and can't seem to find the source of my air leak. The rear of the coach dumps all of it's air over the course of sitting in my shop over night. I have replaced both rear air bags and the five (Norgren?) valves in the compartment under the driver's seat. Still have the problem.

The small on-board air compressor kicks on every three hours or so. Is there a check valve in the system to keep air from leaking back through the compressor?

My mechanic is stumped and so am I.

Thanks in advance for an advice you can provide.

Your coach year model has a unique pneumatic control configuration that the symptom you described will happen if you have a leaky auxiliary air system. Mine is a 1995(with a year or two newer, the pneumatic logic was changed to avoid this issue), so I also have the pneumatic logic that will unload the tag axle air bags if the aux air pressure drops below a minimum pressure. The pressure at which this happens will vary due the mechanical components that initiates the dump. Simply stated, if your aux air drops below what the Norgren plunger needs to release, air will escape from the tag axle air bags during this transition due to low control air pressure suppling your tag axle raise/lower Norgren.

This is very complicated pneumatic logic and is difficult to explain in a message. However, if you would like to chat about this issue, I will be happy to share what I have learned. I have sent you my cell phone number in your private message box.

Hector

Harry Hoppe was having problems with his Air. Kevin Erion replaced several items which were specific to the back end.
I would give him a call.

Does anybody know how to contact John Emmett, N0MHz. I have definitely learned the hard way of how this system works.

Our particular vintage of coach has a few differences in the tag axle logic from newer models that will cause havoc (waste money in repairs) if you are not familiar with the specifics.

I am willing to chat with him in regards to this.

Hector

I just bought a 1997 Featherlite H3-45 and the air pressure just dumps after an hour or so after the engine has been shut off. Out of nowhere, it just goes 'pssssst' and dumps the pressure. Why would it do that?



Jim Lowther
Sarasota, fl

In addition to what Hector was saying another element is occuring. The Lift chambers begin to loose pressure gradually not like the norgren that once it gets to that threshold it dumps all at once.

The lift chambers are slowly pulling on thetag lift chains as the aux pressures drop and before the suspension actually drops.

If U ever heard a popping or knuckling sound in the rear when parked its those lift chains pulling on the axle as the psi is going down but before the pressure drops enough to evacuate the air in the bags.

Jim if yours is losing air that quickly it will be good progress early on finding the bigger leaks because a leak that fast should be easy to hear. U need a Prevo guy with a bottle of soapy water to start the process of tightening up that camper.

John what appears to be ALL the air dumping out in the back I think that may not be entirly correct. When this occures go and check the rear air bags and if my guess is correct U will still have drive axle air bag pressure and only the tag bags are empty?

Jim after rereading the thread I realized its starting date.

Let me pontificate some and try to be of help.

If your camper were new to me Id start it up air it up and shut it off. Then Id begin to go around and open up all the bays and the engine doors and under the driver and Id be looking and listning. As I did, Im sure with your rapid loss of air, Im going to find a few biggies right off.

Then before getting too detailed and isolating things Id check certian components go right to them next, the ones that I know often leak air.

If U have a chassis that leaves the belt tensioner bellows energized with the key off those little bags and the regulator above the door in the engine compartment. If the seat is air the buttons for the lumbar control leak put your ear to them. Never saw a air door lock leak air horns are never leaking. There are lines feeding your air pressure gauges on the dash they will often leak and on both ends. Thats the start on the chassis air common stuff a good start.

House stuff. Yes U have a 1 way check valve on the output of the auxilury air compressor soewhere and when they leak they leak out the air filter for the thing. The air can go right across the compressor head if the reeds are lined up right and ya wont hear it. Seporate the line right at the backside of the valve to soap it and check it.

Common house side air leaks go right to the components themselves first. The generator air bags and their 2 regulators the step slide (put out and look underneeth and soap where the ram comes out) the bed lift if you have air dumps and open the rear wall in the bathroom closet to inspect all the air fittings in there for the pocket doors and such.

If U dothat I am pretty confident that will bear additional fruit.

After I did that then Id go down ito the stearing bay where all that air originates and check all that and begin to determin what if anything in there needed additional attention. In the end when your almost tight thats where U will end up isolating things 1 at a time to find the toughest final repairs. Its also often where U find some biggies right off.

I got my camper to the point where the aux air compressor only cycled 3 or 4 times a day some folks are luckier than other in these terms it is something I managed. In Chicago the bus leaked down quicker in cold yet in the summer it held air really good so its also a moving target U will never stop chasing air leaks as U stop old new will come so get good at it.

Then after U have done that U can go back to the suspension and put it up note the change hopfully completly fixing the ccurrent condition and only then begin to determin what is good and what is bad with those components.

Nother thing too when it goes down Id note the brake tank pressures AND the aux air pressure and Id also verify after it dropped if just the tag air bags dumped or the drive bags dumped with them or are still holding air that is important to helping to isolating the cause.

During the inital process when Im finding the easier big ones U han hear someting leaking from the rear suspension or chassis, when its bad and your leaking good. If u have leaks there thats gonna require putting it up and probably pulling some wheels to help find leaks in that area.

Good luck and have fun.