Air compressor problem?
 

I started the coach today and found no air buildup on the supply side. It pumps full air onto the brake side but 0 on the supply side. I drained all tanks of any moisture and tried the 110v compressor with no luck. Any thoughts on my next move?

Any chance it is just a bad gauge? Did there seem to be pressure when you drained tanks?

No, no air in supply tank and toilet, Leveling system empty. Only brakes pumped up to 130psi. Supply gauge stays on 0

I'm really interested in how this works out since my understanding is that air from the compressor first goes to the supply tank and then is distributed through check valves to each of the two brake tanks. What Larry is experiencing says my understanding is not true.

Recently my service gauge has trailed the rise in brake tank pressures from zero until the brake tanks get to about 40 and then the service gauge will suddenly catch up. From then on they all rise together. I was guessing my gauge was sticking, but Larry's experience suggests something else may be going on. I'm eager to know how what he is seeing is possible.

Does the 110v compressor shut off when the brake side is full? If this is the case it would indicate that a valve feeding the supply side is stuck shut. If it continues running it would indicate that your have a bleed valve stuck open. If that is the case you should be able to hear the air escaping and isolate your problem.

Jon's solution would make sense given the symptoms, but it would also suggest that if you have a leak in the stuff connected to the supply system it would drain one or more of the brake tanks and bring you to a halt when the pressure gets low enough to engage the spring brakes. Every diagram I've seen from the system vendors (Bendix for example) have shown the two brake tanks being fed by the supply tank through check valves. In that scheme the only way the brake tanks can get air is from the at least somewhat higher pressure in the supply tank. Therefore in those schemes; no pressure in the supply tank means no ability to pressurize the brake tanks.

Given what I've just experienced with my water compartment hose connection it may be worthwhile considering that the factory connected the tanks incorrectly in which case what Jon has suggested is as possible cause of your problem. If you have truly verified (and I am in no way challenging what you are reporting Larry) there is no pressure in the supply tank via testing tank drain, pocket doors, toilet and etc then your system must be configured "uniquely" and you will need to get the check valve feeding that tank functioning correctly. While not urgent I prefer to have the system reconfigured to operate in the standard fashion if only to help mechanics in the future sort out problems I may have in the future.

Larry, I hope this helps, send me a message and maybe we can talk if need be.

A couple additional thoughts. The usual way to hook up the air system is to take the output of the air dryer and run a line to the front of the coach to the service tank and then lines from that tank to the other two tanks, one of which is right next to the service tank. If the factory hooked the tanks up wrong I think it likely that the line to the service tank got hooked to the front brake tank and then that tank's lines run to the service tank and the rear brake tank. In that case the problem exists somewhere between the front brake tank and the service tank, that is within a line about 2 feet long with a check valve in it. Other than the check valve the only way to stop the air flow would be if the line was choked off either by being kinked or by internally collapsing if it is a hose rather than tubing.

On my 96 I think that the supply tank is in the rear and the front brake tank and rear brake tank are in the front of the coach with chech valves on each one.

I will try to get at it tomorrow gentlemen. Jon, there is no air to the toilet, freezer or step cover or pocket doors as well as none in the leveling system. I'm going to build my wooden "steps" tomorrow so I can pull up on them to raise the coach High enough to get under it. The air leak that I heard seems to be coming from the front area where the tanks are located. I should note that the brakes hold at 130psi when the air is leaking. I'll keep you informed on what I find.

Larry: wow, you got a lot going on under there, your steps plan is a great idea and one that I will put to use. While I'm a skinny dude, more so in my mind's eye than the mirror, with deflated air bags it would be really really tight.

Larry, Ron: on my 93 coach the rear tank feeds the rear brakes and my service tank is in the front near the front brake tank. While the service tank could be positioned anywhere in the coach the brake tanks need to be close the brakes. When the brakes are applied it requires a lot of air right now supplied through large lines. It would be difficult to supply that air volume from the front of the coach to the brake valve in the back of the coach without an enormous line.

I recently worked on rear brakes and am confident in how mine is plumbed. Others coaches may vary.

Jon: We used to carry a set of those wooden"steps" with us. They are very nice to use as a leveling adjustment on severe slops at race tracks. Had painted them black so they didn't look too bad. Someone decided they were too lazy to build their own and "took possession" of them one day while we were packing up to leave LaGuna Seca race track outside of Montery,Ca. Only in Ca! I never built another set. We used 2X10's but had a trailer to haul them in. They can be heavy and do take up a little space but are nice in the shop.

Well,, back to square 1. There is no leak after the brake tanks are full. The 110v compressor runs but no air goes into the system. I pulled the air line from the 110v compressor and there is air flowing. I can stop the air coming out with my finger but can just barely hold it. I'm thinking that should be enough to put something in the tank in front of the rear wheel, but there is nothing in it. Newell service suspects the Bendix distribution valve located above the cross member between the drive and tag axle may be the culprit, however I'm not yet convinced. That is a major job to change and I wouldn't want to do a "trial and error" repair. I'm not sure I could do it and I can't air up to take it to my service people. Any thoughts?

Have you tried charging up your system with your shop compressor, your 110v compressor sounds a little anemic if you can stop the flow with your finger. As opposed to replacing the distribution valve you might try loosening the fittings to see if you have air pressure coming out of the supply side of the valve.

Thanks Jon. Mike at Newell seems to think it might be the air dryer as both the engine compressor and the 110v comp go thru it while the brakes air up direct . I don't have enough room to get under the rear to loosen a fitting on the distribution valve. I'll check the air dryer first. Let you know.

Larry, I can relate to your problem on a non-coach application where it was the air-dryer and I bypassed the dryer on one vehicle to get it where I needed it and another I bought by-passed by someone else that who knows how long was that way.

Larry, I had to rig up a by-pass for my air drier a couple of years ago. Was an easy task just needed to get some 1/4" pipe fittings at hardware store.

Thanks for the input Ken and Clint. That's the next plan. These are the times when I wish I had a way to lift the coach.

You might try picking a couple of these up.
Attachment 4451
20 Ton Air Hydraulic Bottle Jack

print the coupon: Coupon Display

Jon, those would do the trick as well. I recently picked up a nice air over hydraulic floor type jack. I also obtained some other equipment with anticipation I may acquire another coach mainly in need of repairs. I passed on two this month and both were damaged Newell's. One was a '05 quad slide and the other today was a '01 tripple slide. Both need front and other repairs. Both were very good deals. I have pictures I may share of them some time.