[Art]

Chuck, You are correct in where and how you looked for leaks. However they have a way of hiding and in some cases there is no device known to man to isolate them.

I’ll suggest a couple of things assuming my understanding of your suspension system is correct. (They have evolved and have subtle differences) If your coach has a single 3 port Norgren in the steer compartment from which air is exhausted when you lower the coach, plug the exhaust port and see if it stops or slows the leans. If it does it suggests to me air is leaking past the 5 port valves.

That was the low hanging fruit. Now it gets difficult.

Assuming you found no leakage around the end caps of the Norgren valves, at any of their fittings, out the exhaust tube of the 3 port valves on the frame between the tag and drive axles the only thing left is air bags. What makes this less likely is you said the coach settles somewhat evenly all around. But there is a possibility more than one air bag has a leak due to age or a manufacturing defect. This is a shot in the dark so make sure you checked and double checked everything else. I’m assuming you included the ping tanks, their drain, and under the straps where potential corrosion lurks.

If an air bag is leaking due to corrosion in the bottom can, or around where the rubber joins the bottom can you cannot see bubbles because of the plastic “piston” the rubber rolls up and down on as the bag extends and contracts, so your only way to determine if that is the place the leaking is happening is to rig up a fitting to go into the top of each air bag, inflate them one at a time and verify they hold air.

There is no easy way. Prevost may still have a policy that if the coach stays up and level for three days the system meets their standard for acceptance.

[Jim/Chris]

My leans were caused by tag air bag on passenger side was bad it had a crack in the rubber where it rolls around at the bottom. It was hard to find it had to be in a certain position to find it. Replaced all the bags because they needed it.

[Loc]

Jon:

I did not check the end caps of the Norgens, just the fittings where the air hoses connect. Back under the bus for that. Also did not check the straps on the tanks, more time under the bus.

Art:

Just had my front bags replaced but the rest are older, will check as best as I can for now. More time under the bus

Guess you can say this covid-19 has really thrown me under the bus. (Just trying to put a lighter moment in a serious situation).

[George]

Chuck, if you end up failing to find leaks give consideration to the air bags regardless of age. As Art posted older air bags crack and begin to get slow leaks, but where the top caps and bottom cans join the rubber leaks can also develop.

The reason for checking end caps on the Norgrens is the O rings on the spools can leak at the ends with air escaping around the perimeter of the end cap. They are not sealed.

[Jerry]

When you check the air bags, raise the coach as high as possible with the airbags. This does 2 things exposes parts of the air bag not normally exposed and raises the air pressure in the bag as high as possible.

Remember to “re-block” the coach before going under it.

[Joe]

Been side tracked, air hose under drivers seat ruptured & washing machine in house quit. between chasing parts for seat and shopping new washer and dryer haven’t devoted any time to air leak.

Strange thing that may or may not be related to the slow leans. Since the air hose ruptured on the drivers seat the Aux tank was depleted because I did not have the Aux compressor on. It has been about three days now and the coach has barely gone down at all. Don’t know if having the Aux tank empty quickly has anything to do with it. Was wondering if having air in the aux tank is keeping a valve partially open and when the aux tank lost air quickly because of the drivers seat a valve was able to close without the aux tank side pushing PSI on it. Just stabbing in the dark here.

Chuck

[John]

Your Norgren logic may be different from mine. On my 93, when the aux tank reaches 35psi, the 3 port Norgren switches and vents the tag bag. That is the Norgren which signals the tag to raise or lower. I plugged my vent port so I can not raise the tag but, I never raise the tag so I don’t care. When it vents the right and left sides may vent at different rates and so it looks like it is settling more on one side.

that logic was changed in later coaches but Jon will have to say when.

[Gerald]

It was a service bulletin so coaches with the original logic could be updated, but production units went to the more common logic in the mid nineties.

Prior to that aux air pressure was needed to prevent the tag axle air from being exhausted, and after that change aux pressure could go to zero and air would remain locked in the air bags.

[Harry]

Jon:

Your suggestion to recheck the Norgren was correct (see Picture). The front Passenger side Norgren was leaking at the one end.

I also used the level low to raise the coach all the way up to check the bags (didn’t find any bag leaks). The front exhaust tube on the front Norgren was leaking a little in the level low up position but stopped leaking once back in ride height?

As noted in my first post the coach settles almost evenly and slowly with a very slight lean to the passengers side. I have found no leaks in the rear of the coach, I am wondering is the Norgren on the front passengers side having a slow leak is allowing the entire passengers side to settle just that little bit more than the drivers side and it just happens to be a bit more noticeable at the passengers rear because the passengers rear mud flap is closer to the ground than the front when in normal ride height and the rear appears to show the reduced ground clearance sooner.

Chuck

[Archived]

Always great info here… Thank you for sharing all the details, Chuck. No doubt your determination will result in a victory!

[DON]

Good job, Chuck. Chasing leaks is frustrating and there are so many places for leaks to hide there is a great deal of satisfaction when one is identified.

[rafael]

If any exhaust port is leaking the Norgren spool is leaking. Change it.

Check that, it has been a while since I looked at the logic but the 3 port in the steering bay may always be open which means one of the 5 ports is leaking back.

[Archived]

depending upon how old the coach is – i wouldnt change spool valves but to just order a complete replacement of the norgren unit. . . . many older ones (like my coach), if you even try to replace the spool valve – the screws that hold the cap on will strip/break and essentially render you inop until you get a replacement norgren unit. the screws are steel and the unit is aluminum I believe – which causes galvanic corrosion over the years.. . so unless your screws are in excellent condition and you know you can get them all out safely, I would have a replacement unit ready to go. . . .