suspension problem; airbags?

[coolbus]

I'm puzzled as to what is going on with my suspension. If I park the bus for a while, or drain all the air from the air lines, the bus settles down to the stops on one side, but the other side remains up off the stops (in the rear, anyway) which causes a considerable lean to the whole bus.

Seems like I should be able to dump all the air to make the bus sit down evenly on the stops.

Any idea what is keeping the one side from comeing down?

Thanks

Mark

[coolbus]

The bus is a 1968 Prevost Champion

Thanks

Mark

[DavidInWilmNC]

Isn't there (supposed to be) a check valve between the leveling system valves and the rest of the air system?  I know on my MC-8, the air can read close to '0' but one side is down and one is at full height.  This happens if I open the drain valve in the engine compartment and drain the air tanks.  I'll tell you something even stranger.  When I first got my bus, it would lean towards the driver's side in a day.  I replaced a leaky air bad and a flaky leveling valve.  On the road, it stayed level, which isn't surprising since the compressor is keeping up with any losses.  When I parked it at the campground, it leaned towards the passenger side for the first time.  When I got it home, it's within half an inch of being level.  It's never stayed level for even an entire day.  Somebody on this forum told me that if I drove it a bit, a lot of those 'mysterious things' would work out.  Of course, I thought yeah, right.  Well, after a 700 mile trip, it's sitting level, so who knows.  I think some of these problems will be taken care of by a manual level override system.  A member on this forum has a kit for this.  Good luck with it; I swear these buses have minds of their own.

David

[Stan]

The only control on the air bags is the leveling valve which maintains a fixed distance between the chassis and the axle. If that distance is too great (load has been removed) it will let air out until it reaches the set point. If the distance is not great enough (load has been added) it lets air into the bags.

If this is not what is happening, then there is a faulty leveling valve or a leak in the suspension system. Obviously, it cannot add air if there none in the air tanks, but empty air tanks by themselves should not cause any change in bus level.

[FloridaCliff]

Mark,

If everthing was working right(as built) it should stay up with no air on your gauges.

It may slowly leak down as you walk around after shutdown due to the leveling valves discharging to adjust.

Sounds like you have a leak on the side going down right away.

HTH,

Cliff

[coolbus]

Thanks for the quick responses!

I think I understand what is going on now.      Yes, there probably is some leaking going on; probably more on one side of the airbags than the other. 

Since the air has leaked down on one side, is there a way to simply drain the air from the other side so it will sit more or less level?

thanks again,
Mark

[Barn Owl]

I am one of the lucky ones; my airbags will stay up forever. I have gone months and the bus will still not be near the stops. The gauges however, will drop out in a couple of hours. While on vacation though, the gauges started holding air overnight, I was waking up to 70lbs after sitting 10 hours. Only a couple of days after being home I was back to zero after only a few hours.

What about shooting the system with a can of fix-a-flat? ....... Just kidding

[RTS/Daytona]

A-
Fix/Replace any leaking Height Control Valve and Air bags or tubing to the Valve

B-
Go to your local hydraulic or truck repair shop - get 3 DOT approved tee fittings and slice into the air line between the leveling valves and the air bags (front usually have one leveling valve teed to both front air bags ----
use DOT approved nylon suspension/brake tubing and bring the nylon lines out and install DOT fittings with ball valves mounted in a inconspicous place - to open to dump the air - remember it will dump ALL the air in your suspension system and then will also bring down the other tanks usually to about 60 PSI (due to the action of the protection valve (protection valves - prevent suspension catastrophic failures from bring the brake system pressure lower than 60 PSI   

C-
or you could buy my campsite air bag leveling system ?? - BUT - you would still have to fix/replace any leaking air bags or tubing to the valve

Pete RTS/Daytona

[Kristinsgrandpa]

If parked level, my front stays up for 6 months, but the rear only stays up for about 6 minutes.

Ed