[pairodice]

I decided to time how long it took from fully raised air suspension to flat.  
After several non-starts it took about 3 hours to be completely out of air with both the air compressors off. It may have been less but that is an approximate number since I was checking every half hour or so.  The 110-volt compressor seems to run about every hour is we don’t use anything inside with the coach raised all the way up.  
Is this about average?  
I know I have a leak in the air valve/solenoid for the Dupree waste valve and am going to order the parts for the rebuild... 
Seems like the ‘Brake’ system lasts longer so maybe the brakes/lines are not leaking down as fast...

[Richard]

We can deduce a couple of things from this. The first is that your PPV Pressure Protection Valves on both your primary and secondary brake tank need to be replaced. Your brake tanks should not leak past about 90 psig in three hours. What would make them both go kaput, moisture leading to rust leading to debris in the system.

Second, you have a moderate air leak somewhere, and you may have found in either the Dupree valve and/or the actuator that operates the valve. Both can cause a hefty air loss.

Take some time and read a basic primer on how the air system works, and it will help you understand the brake side of the system. https://www.suspensionspecialists.com/te...k_2009.pdf Don't panic, the first couple of pages have the concepts you need to grasp. Then take a look at the posts that @"rheavn" made on finding air leaks.

[Jackflash]

Where are the PPV's located and are they Bendix or Haldex?

[pairodice]

I thought a PPV was a ‘People Powered Vehicle’ - what is it really?
Never mind, I reread your post and see it’s a ‘Pressure Protection Valve’ ... no idea what it is or where it is located...

[encantotom]

on my 02 the brake check valves are on top of the brake tanks up front. not easy to get at. there is nothing special about them. any truck parts place will have them

basically the concept is that the brakes take priority over everything else. if the supply side has more pressure than the brakes, the brakes will take air from the supply side. it does not work the other way around. the supply side will not take air from the brake side.

tom

[Rongripon]

I am having a leak down problem and the 115vac compressor doesn't seem to be putting out pressure. not sure if its the internals of the the Thomas comp. or something else. trying to find a good test to see if its putting out..any help would be great.

[Richard]

Take the air line loose from the end of the pump. Screw a gauge into the fitting. You will be bypassing the pressure cutoff switch, but its a quick and dirty way to see what the pump is doing and the max pressure the pump is capable of producing.

[Rongripon]

It looks like the pump isn't producing pressure. Now the worst part. all the air, brakes, slide seals and anything else than cam dump is empty. I can start the engine, build pressure and believe I can drive.

I'm looking for leaks and have found a few and fixed but it has got to be a big one. with out the compressor running it goes down.

Any ideas.

[folivier]

Ron if you'll be parked with electric hookups you can buy an air compressor and use a double male quick connect to attach to your coach air quick connect (probably in the right side engine compartment) and let that keep your coach aired up. Harbor Freight and Lowes/HD, etc. have fairly cheap compressors.
Your engine running should keep everything aired up while driving, assuming no massive air leaks.

[Rongripon]

OK, here is where I stand:

put a gauge on the output port and it will get above 110, drift down slowly to 0.

no air pressure on the brakes

no pressure on the slide seals.

airbags seem to be holding pressure with the Valid leveling system off.

I can start the engine, build pressure and all looks good BUT?????

all this time, the doors are operating and toilet operating as it should

THIS CAME ON, OUT OF THE BLUE, SEVERAL DAYS AGO. IT IS GETTING WORSE.

anyone have something i should check, please let me know and THANK YOU ALL.