Bus un-levels over time

Jasper when you say the passenger side raises are you talking about the front end or rear end or both?

We had the right rear of our coach raise up about 2" at the Kerville rally last year. We cycled the Prevost level low solenoids/valves, and we have never had the problem again? If the rear is un-level it will cause the front to be unlevel as well, unless the front suspension is sitting on the bump stops which would tend to help hold it level. Our coach has the standard Prevost Level Low, and our aux system was at about 100PSI in the morning. We did not have our aux compressor on. My guess was that the rt rear solenoid valve did not seat completely, and was letting the air from our aux system pressurize the rt rear bags.

OK folks, here is some realtime information; and by the way thank you for taking the time to help. That is what makes this group special....and some sheep???

When the bus is leveled using HWH (Level-driverside) 6.75'' from ground (Level -passenger) 10'' from ground
When the bus isn't level using HWH (Un-level -driverside) 6.5'' from ground (Un-level-passenger) 13'' from ground.

So, can a 1\4 to 1\2 inch fall on the drivers side translate to a 3'' lift on the passenger?

the rears were equal at 17'' on both slides. "may pad has some dimensional run outs"

Yes it can rise as has been pointed out, but to do so involves either some perfect combination of valve leaks plus maintaining a good auxiliary system pressure (which you previously stated was down to zero) or the HWH is trying to reach a level condition that is different from the original one.

The bus cannot go up unless the air pressure to lift it is avalable. That pressure can only come from the aux air system (never from the primary or secondary brake circuits).

Have you tried to measure what happens if the bus is leveled and then the HWH is not attempting to level it? I assume that auto-level feature can be turned off?

Did this just get ignored?

I have had this system before and the process you describe would lead me to the HWH sensing adjustment located somewhere in a bay, usually on the ceiling of a bay. This is where the leveling system get's it's information and may need adjusting. You would first have to manually level and then re-adjust the sensing device.

I wonder if there is some sort of sensor with the HWH system that may be at fault - anyone have any ideas?










:cool:

I do want to clarify one thing; the air pressure in the aux tank goes to zero only when I kill the breaker for the compressor. (clearly a sign of a leak). When I leave the compressor on the bus still get out of whack, the aux tank remains pressurized, but the compressor cycles. (cycles about every 2 hours or so)

Jasper,

There is one thing that owners have a hard time embracing. The bus, if leak free in the suspension system, will sit level regardless of how much pressure is in the auxiliary air system. If the aux system is zero, the bus will not necessarily lean or drop.

If your bus is rising because you have pressure in the aux system the diagnosis has to start with the HWH system to make sure it is set to "level", then the solenoid valves to make sure they are not holding pressure against the Norgren 3 and 5 port valves, and then the 3 and five port valves to make sure they are not leaking air pressure into the rear air bags.

For your problem to be the perfect combination of valve leakage seems extreme. I would give special attention to the HWH as Truk indicated.

When you level your coach are you using the HWH exclusively or both the HWH and Level Low? When I level my XLII I use both the HWH and Prevost Level Low. I first put the Level Low in one of the non-drive positions (it doesn't matter which one), then I engage the HWH and level the coach. Once level, I turn off the HWH and the engine (it is much easier to level the coach with the engine running than relying on the aux air compressor). With the HWH off and the Level Low set in the non drive position I have yet to experience any unleveling issues with the bus using this procedure. I did find a couple of times that if I did not switch the Level Low to the non-drive position the bus would change level.

Loc's post reveals something that owners have to determine. How did your converter set up your suspension system and the HWH?

Does it function with the key off? Does it operate all the time? Does the level low have to be in a non driving position in order to funtion as an automatic leveler? Can the automatic leveling be turned off?