Rear Air bags

PeterH-79MH · 03-16-2002, 01:51 PM

ALANSD wrote: <<<<<I checked my rear air bag valve and found no air in them. I tried to air them up to 100, never got past 50psi, then by them time I rechecked, they
were at 0 again. I guess I see why the rear seems "bouncy"- any ideas on how to isolate the problem? It could be the small tank, or the lines , and of course the bags...I wondere if the compressor was coming on as I never hear it, guess the whole system could be replaced..>>>>>>

Besides being bouncy, you must be very low in the rear.
With the system @ 0 psi, the aircompressor should come on, when you turn the ignition on.
Check air compressor fuse. You could have burned out the compressor.
Use a spray bottle with water and liquid soap. Shake the bottle to make it all foamy and spray all the fittings and the 4 valves mounted on the leveling valve bracket.
try inflating again. If the air loss is as rapid as you describe, I suspect a leaky bag.
Don't think about replacing the entire system, too costly.
If this does not show you anything, get compression fitting type plugs at your local plumbing store. First plug compressor side of tank, then airbag side, to isolate.
more later

ALANSD · 03-16-2002, 03:38 PM

It doesn't seem very low in the rear , actually sits level as measured by a level in the kitchen area. I checked the air pressure at the valve on the bottom of the accumulation tank, which sticks out the bottom of the rear luggage box whwre the compressor is located. There are two spring loaded screw ins that I am not sure about as per function, a large one and a small one side by side under a small grey cover over the wiring for the air sysytem. I would assume the air pressure should be checked at this valve- looks like a tire valve.

PeterH-79MH · 03-16-2002, 04:02 PM

The spring loaded screws under the grey cover are part of the pressure regulator. They determine cut-on/cut-off pressure, which should be ~70 (compressor turns on)~100 compressor turns off.
Don't mess with them, unless you have a pressure gauge inline.
Have you tapped on your airbags, do they feel hard. You know, when they are flat.
There should be a check valve in the system, that does not allow air to feed back into the compressor.(because they all leak!)
If that check valve is located on the air bag side of the tank, your bags could hold pressure, even if the tank is empty and the compressor is broken.

ALANSD · 03-16-2002, 07:06 PM

I will check it out further tommorow. I haven't yet checked the fuse for the compressor. I checked air pressure at the vavle coming out of the bottom of the accumulator tank, and that was where I was trying to add air as well, as it read 0. The bags do look inflated to me, althought the ride is a bit bouncy in the rear, not so bad as to hinder driving, but still not as it should be. That's what made me check in the first place. The manual says this valve can be used to add air, so I assume its where you would check system pressure?

Here is a quote from info I had saved in my collection if anyone else needs this-
"I had a problem with my air bag compressor. It would run hot smell strange and some times blow fuses. I decided to replace it. I purchased a heavy duty 12 volt compressor from the local department store, rated at an eight hour duty cycle and a 250 lb. capacity. I wired it directly into the regulator switch that is in the compartment, and I plumbed the the hose end onto a barbed fitting with a back flow preventor and an air nozzle inlet for emergencies. The whole thing cost about 50 dollars and it is working great. "
also this one

"I had the front and rear shocks replaced on my MH with the bilstien shocks specified for the P30 from camping world. All works well."

PeterH-79MH · 03-16-2002, 09:45 PM

I only have a drain plug on the bottom of the tank. For many reasons, I decided to install an inline pressure gauge, which reads the pressure from the compressor to and including the tank.
During ignition on, the pressure reads 80-100psi, when reaching 80, the compressor kicks in.
When ignition off, the pressure may drop to 0, if parked for long periods of time, but the bags always stay fully inflated.
Two things keep the bags inflated, even if the pressure is 0 at the tank/compressor side:
1. the solenoid valves that are closed with ignition off.
2. the check (or back flow) valve, which I placed on the air bag side of the tank.
I guess the factory set-up would be to have the small inline check valve right at the compressor, but that means with a tight system, your compressor may not turn on for weeks.
With my set-up, the compressor kicks in every few days, which is assuring.

thenewkid64 · 03-17-2002, 07:32 AM

Alan,,

My MH does not have the automatic compressor, I have front air bags aftermarket installed. When I got home for our first trip I checked the air bags and one was at 0 the other at 40 PSI. On my bags there is a valve at the bottom of the bag where th inflator hose attaches. That hose was loose and allowing all of the air to escape.

I do not know if your setup is the same but in talking to other MH owners this is a trouble spot. I wonder if the compression/expansion of traveling causes the bag to rotate in place, thus unscrewing the hose??

I may have to dissassemble and reinstall with some loc-tite.

Just my 2 cents

JW84345 · 03-18-2002, 10:41 PM

I had new front air bags installed inside the coil spring when I picked up my coach in Phoenix last year. I noticed one of the air bags deflates over time. They should be inflated to 55 psi. It makes a huge difference in how the coach handles. I suspect the same problem you describe causing the leak. I'll check it out next time it is nice enough to craw under the coach.

Alan, does your coach have a Tag axle? If so, it is very important to keep the rear air bags inflated to the proper level. On my coach, the compressor pressurizes the accumulator tank. There is a mechanism attached to the tag axle that opens the valve between the accumulator tank and the air bags when the rear of the coach is sitting too low. In this situation, the Tag axle is taking more weight then designed for and the main axle less. The bags inflate (more) raising the rear of the coach until the coach again sits at the proper level to balance weight between the main and tag axles. The compressor runs when I turn on the ignition if the coach has been sitting for a while.

Jim

ALANSD · 03-19-2002, 08:53 AM

No, mine is a single axle dual wheel. I believe the bags are inflated, although I don't think the compressor is coming on..
The coach sits level and doesn't ride too bad, but as I had said it does bounce a bit in the rear making riding back there not the most pleasant.
I am going to get new shocks put on soon and have the tech look into to air bag situation. It may be that the valve sticking out the bottom of the accumulator tank is not working right. Its an inexpensive tire type valve, sticking through the bottom of the rear storage locker, where dirt and crud could really affect it.
May get the shocks before the rally...

ALANSD · 04-03-2002, 01:09 PM

I had new rear shocks installed, the old ones were completely worn out. The technician said the air bags and compressor are fine. He told me that the valve at the bottom of the accumulator tank would allow air to be added when an inline valve was opened, and otherwise this valve would only release moisture from the tank when depressed. A relief for me, as the system is doing what it is supposed to do. Now on to Mystic Springs!

ALANSD · 10-27-2005, 12:48 PM

so after three yrs of messing around , I removed the compressor, checked all the lines, removed the tank which had rrusted through...added a schrader input valve, and all is well. Air ride is sure sweet.

rvlover · 12-05-2005, 08:38 AM

I have a similar problem...79 28' center bath...woke up from my first and only camping trip with the air bags empty...bypassed the pressure switch to cut the compressor on with no luck...filled the holding tank with an aux compressor with no air getting to the bags....two weeks later I pulled the cover off the pressure switch and the compressor came on and filled the bags..installed new pressure switch and all is still working after 5 days...po said solinoids are wired to pump which is wired to switch which is always hot....I hate to have this happen again out in the wilderness...any suggestions...joe

swebster · 12-05-2005, 11:35 AM

Joe,
Sounds like you found the issue. The two big things with the bags are water in the tank and cracks in the bags. Other than that it's maintenance of the compressor, solenoids, etc.

One thing; why didn't the bags fill up with your pressurized the tank from an outside source?

ALANSD · 12-05-2005, 01:00 PM

The bags are holding air now? For awhile mine seemd like they were holding up. The hole in the tank must have been smaller, and it eventually just rusted though. Now its simple for me I have no compressor, no tank, no switches or power lines to worry about. Just a manual valve for input.

So here is a question- can these be overfilled? Or does the check valve bleed off the correct amount of air to maintain the pressure? I am thinking this is a no....and I need to be careful how much air I put in.

rvlover · 12-06-2005, 08:07 AM

This is the first air suspension I've been near so I know nothing...I think the bags failed to fill when I applied air pressure because the solinoids did not open....po said wired directly to compressor so open when pump comes on...but at one time I had compressor on with bypassing the pressure switch and also adding outside air pressure with no increase in bag ride height...I hope air was going to least pressure like out the compressor instead of in the bag...to be safer I'm thinking add something to add air directly to the bag...any thoughts??? joe