Re: Our leveling system problem
Reply #37 –
Steve and Michelle,
Thinking about your problem, it appears that you have at least 2 leaks. Air is leaking into the front air bags and leaking out of the rear air bags. Since you have replaced all the o-rings, the leak most likely is at the seating surface of the valve/valves. For each set of air bags (2) left front, right front, etc. 2 solenoid valves admit air and 1 valve exhausts air. When in the travel mode the travel solenoid valves are always open and the HCV admits and exhausts air. When all power is off, all the solenoid valves are closed. The leveling system when in use closes and opens the other 4 solenoid valves on a manifold to admit and release air on an individual basis for a set of bags, but more than one can be open depending on buttons pushed or what the auto leveling is doing. The HCV valves are always trying to exhaust or add air except when in the neutral (correct ride height) position. With the travel solenoids closed the HCV's cannot do either. A leaking travel solenoid would send air to the HCV, but the HCV unless defective would not raise the air bags past travel height. If it maintains the proper ride height in the travel mode the HCV is okay. Therefore it appears that both front "air in" manifold solenoids are leaking. You did not say if one rear side was lower than the other, if so this can also cause a difference in the height of the front air bags. Since the rear is lower, suspect a leak in an exhaust solenoid there. On my coach the top solenoids are the travel solenoids; the middle solenoids are for exhausting air; and the bottom solenoids admit air. Could be different on your coach, but most likely it is the same.
Try the same procedure tonight except after the coach is level, pump down the brake tank pressure to about 60 psi and see what happens. The front bags should not inflate as air will not be available to inflate them. It is possible that they might leak down though if pressure in the bags is greater than in the tank.
The solenoids can be disassembled to inspect them. They are rather simple devices. Just unscrew the steel part from the brass part. There is a cone shaped seat, a piston like plunger with a plastic insert that rests on the seat when closed and a spring to keep it closed when the solenoid coil is not energized. The wiring does not need to be disconnected to remove the coil which is held on by one nut. Then the valve can be unscrewed from the manifold. The manifold should not be pitted where the o-rings seat. A little grease on the o-rings is recommended. If the piston plastic seating surface has more than one indentation from the cone shaped seat, that could be the source of the leak. That was the case on one of my solenoids. I was able to correct the leak by chucking the piston in a lathe and removing just enough of the plastic insert so that is was smooth again. The internal parts of the solenoid are not available except for o-rings, and the coil, from what I have been able to find out.
Topic: Our leveling system problem