Leak in air supply

[The_Money_Pit]

Originally Posted by Dennis

I ask the because I have a front slide out seal leak, but have had this leak for almost 2 years (repaired it once, but it did not last) and the slide and Coach worked fine (aside from the hiss). One possibility is that the air leak in the front slide has become much worse and as such the air is leaking out much faster. But I would be surprised that a seal leak would disable the Coach from being driven because of low brake and air bag pressure.

Originally Posted by lnchaffin

You can cut off all air to the slides by turning the dump valve on the air manifold. This will eliminate the slides leaking but you would be able to hear a leak that big.

My best guess is the problem is your slide air leak. The slide air leak is so large it is depleting all your air. I would follow the above recommendation. I do not have a slide coach and I don't know where he is speaking of.

My bird had difficulty in airing up the airbags, one side would air up faster than the other. I was losing air pressure while driving down the road fairly fast. Engine air compressor was cycling on a lot. When docked my aux was on all the time. The leaks that I found at the two PPV valves seemed really really small, and I thought that I must have a larger leak somewhere, but no, those two small leaks were all it took to bring the air system to its knees. I am not saying you have a PPV leak, but your slide air seal leak could easily be the source of all your headaches.

[lnchaffin]

Dennis,

Go to M380 (unique issues) section and look at the thread labled "Slide with loss of air" and you will find all the info you want about slide air issues and how to turn the air off.

[Dennis]

Thanks I will try cutting off the slide air and test this theory.

Dennis

[Dennis]

Okay, I cut off the slide air then ran the aux air compressor for about half an hour; little happened except the right and left brake air came up a little. By the way the brake air pressure did NOT bleed or leak down, it stay up all night at just below the 75 psi that it reached yesterday. After the aux air compressor did nothing much I started up the Coach and let it idle for a while, the brake air climbed a little to 75 and stayed there. When I put the fast idle on the suspension did come up, not to full level but up a few inches. All the warning lights when off.

When I shut down the Coach I walked around and stuck my head in every opening and could not hear a hiss anywhere, not even in the slide seal since I cut off the slide air. So what this tells me that the air leak if there is one, does not have anything to do with the slide air leak

The only noise I did hear both when the engine was running and when I shut it down was in the bay where the aux air compressor is. There are two noises that never where there until I had this problem. One noise is definitely coming from the "pumptol" and it sounds like when there is a bad bearing. The other noise seems to be coming from that small air tank/cylendar and it sounds like almost like water running through plumbing - like air being pumped into the tank. Sometimes the sounds coming from that bay sound like "groaning". I don't know if this is what is causing the problem I do know those sounds never were there before this problem. I touched all the lines and plumbing going into the tank and pumptrol and nothing different happened.

I get the feeling that the problem is not a air leak but under performing pump perhaps having something to do with the "pumptrol."

Any thoughts?

Thanks,

Dennis

[Robert Britton]

The noise you describe from the aux air tank is probably air moving through the system…need to figure out where it’s going.

When you start up the coach you should try leaving the suspension dump switch in the dumped position; then see if the coach will build air pressure.

When the coach was running, did you check the air dryer to see if the purge valve was blowing air (stuck open) as the system was trying to build pressure? You can access the air dryer through the left rear louvered compartment(compartment where sewer hose is stored). It's behind the oil cooler, the big round thing. I know the aux pump sends air to the air dryer before going into the coach air system, maybe that’s where the air is going that you hear moving through the aux tank.

Try leaving the aux compressor off the next time you start the coach…see if you still hear that sound after shutting down.

[Dennis]

Thanks Robert I will give your suggestion a try after work today. Actually I intented to recycle the dump suspension switch yesterday, but forgot to do so in trying everything else.

The "groaning" sound in the aux air compressor bay that was not there before this problem almost sounds like an obstruction in an air supply line; like air was trying to get through a narrower opening.

If the air dryer release valve is stuck open or partially open would the Coach suspension dump after the air pump is turned off - because the suspension does come down at idle?

I know the location you are referring to, but what does the air dryer look like and where is the valve located on the dryer?

If I leave the suspension dump switch in the dump position and start the Coach what should I look for? How will pressure build up with the dump switch in the dump position?

Lastly, through all these exercises the aux air compressor never went on except when I turned the cockpit aux air compressor switch on. As far as I know that aux air compressor never has gone on except via the switch - I get the impression from reading this thread that it is suppose to cycle on automatically when needed? Perhaps (I don't know) the problem I hear in the pomptrol devise is why it does not automatically turn on????

Dennis

[Dennis]

Robert,

Here's the report. I did everything you suggested and with the same result that I had before. Then I noticed the sound of air escaping from somewhere in the area behind the firewall of the aux air compressor bay - the area under the driver's chair. This is the same area that I am hearing that "groaning" noise which at times I thought was coming from the small air tank in the same bay, but is really coming from the otherside of that firewall. I don't know if it is from the suspension valve or a hose or? I will be bringing the Coach into the shop on Tuesday instead of Wednesday - at least now I can direct them with some evidence to a probable area.

Any idea what is behind that firewall besides the suspension dump valve?

Thanks again to all of you for your help on this.

Dennis

[lnchaffin]

Dennis, I can tell you that several of us have had problems with "Check Valves" in that area going bad. There is a check valve on the air tank and one on the 120v aux compressor. I have had both of mine go bad and cause problems but not similar to the conditions you are having.

I really think if your "Main Engine" compressor is working normally and you let your coach set at 'High Idle" for a few minutes and you have a leak some where you should still pump up to over 100psi. I am confused as to why you can't get over 75psi. That just doesn't seem possible unless you have like a hose blown off and you definitely should hear that. Something really strange is going on and you really need a tech to look at it. You said Aux compressor will not pump up system either so that mean you have a problem in the air dryer or some where after that. Both the engine compressor and 110v compressor sends air straight to air dryer. I mentioned to you having your dryer serviced....maybe it is stopped up if it has never been serviced in 7 years??? If you have never done it then maybe it has never been done?

[iamflagman]

Originally Posted by Dennis

I know the location you are referring to, but what does the air dryer look like and where is the valve located on the dryer?

Dennis,

I'm not sure which air dryer your 'Bird has but here is some reference material, that you can download onto your computer.

Wanderlodge Owners Group > Mechanic's Corner > Tires, Brakes, Steering and Suspensions >

BENDIX AD-1 AD-2 SERVICE DATA.pdf
BENDIX AD-9 SERVICE DATA.pdf

This catalog is very large but worth having for parts identification purposes;

Bendix Quick Reference Catalog

[Dennis]

Thanks Lloyd and John. I will print your comments for my mechanic (tech) and of course let you and the Group know the outcome. The noise that I heard when all this started sounded more like a blockage than a leak but I would think if there is a kink in the line or some other blockage the pressure would build up and blow out the pressure release valve. Have a great Holiday weekend; more as I find out.

Best,

Dennis