[Fred F.]

Try this highly scientific cure……

I would guess it’s a sticky valve. Machine gun the level low button and it should be OK.

[Archived]

I did try turning level low on/off quickly several times. No go.

As a next step I’ll take the coil off and remove the valve and see if it can be cleaned.

Would be nice to have a spare/replacement though. I read through most of the pneumatic section and found some part numbers others have used 641107(coil) and 641353 (valve). But when I check those numbers on Prevost Parts online, they don’t seem to be valid any longer. Has someone replaced one of these valves recently?

Thanks, Gerald

[Archived]

I am assuming the culprit from the description is the top solenoid valve from the 5 valve manifold in the steer compartment.

It could be one of the O rings at the base of the valve body or it could be the valve itself. It is an easy replacement if you can get the valve. The valve needs to have the coil removed which is done by removing the snap ring. The valve body is held in place with two diagonal phillips or torx screws. When the valve body is removed, do it carefully and note that there are two O rings, a very tiny one in the center and a larger one around the perimeter.

A new valve comes with the O rings. Just make sure the valve mounting surface is clean and neither O ring is still stuck on it. I use a dab of white lubricant to hold the O rings to the valve body during installation.

These valves when open send a signal to the actuator port on the Norgren spool valves, and when the switch in the coach is off and the coil de-energizes, the valve not only closes, it exhausts the air pressure in that line. If it did not de-pressurize the Norgren valve actuator the Norgren would still remain in the energized position. The reason that is mentioned is because if you still hear air escape after replacing the solenoid valve the leak is in the Norgren valve and air is escaping around the O rings in the spool valve into the actuator, and then out the solenoid valve in the steer compartment.

[John]

[Archived]

Good job Truk.

[Archived]

Gerald, when your coach leaned during your oil change, did you miss a very

important first step? Would like to see many more post from you

[Archived]

Jon, thanks for your explanantion. Looks like I have either (1) a stuck spool valve in the rear that is exhausting aux air through the valve in the steering compartment or (2) the valve in the steering compartment has an O ring failure and is exhausting aux air source locally.

It is probably a stuck spool valve because as long as I raise left rear corner of the coach, the valve in the steering compartment stops exhausting

One more question: Assuming it is a stuck spool valve in the rear, how does the coach stay at ride height?

Joe, good point about supporting the coach. I have it on ramps with backup safety stands.

Appreciate the help

Gerald

[Archived]

I doubt if the valve is stuck, just more likely air is escaping past the end O rings into and likely past the actuator piston. If the valve was stuck in one position you would not be able to shift from the ride height valve position to the off position to the level low position.

As to why the ride height is maintained, the Norgren shifts to open a path through the ride height valve to the air bag. If Air is supplied through the center solenoid valve to the actuator on the 5 port Norgren to hold that path open. Unless the leak is huge the engine driven compressor will always supply air in ample amounts to keep the bus at the correct level.

One thing that I always fail to mention as a contributing factor to unusual operation of the suspension system is moisture. I worked on a coach that would be raised in the driver’s side rear manually, but in the road position it would go and remain all the way down. It turned out the pneumatic system had been pretty wet at some point and a sludge of aluminum corrosion that had accumulated prevented the Norgren from shifting the spool in one direction.

The simple way to diagnose the problem is to swap the solenoid valve with one of the other ones on the manifold. If the leak follows the solenoid valve that is the problem. If the leak stays with the original leak position the problem is elsewhere.

[Steve]

It turns out it was the first solenoid valve that controls the air supply that was the problem. I removed the coil and valve, The valve seat and o-rings looked ok so I proceeded to open the valve itself. I did not really see any contamination and the plunger and spring seemed to move freely. I cleaned the plunger seat with alcohol, reassembled and applied aux air pressure – No more leaks. Hmmm.

Not sure this is a permanent fix. I’ll give Prevost a call on Monday to order a spare valve and coil if available. The parts book does not show individual valves and the whole 5 valve manifold is $360 online.

Thanks for everyone’s help. I learned a lot from your responses, Jon’s article on this site and the Prevost Level Low webinar.

Gerald

[Archived]

Prevost may not even sell individual components any more. Feedback we have gotten from previous posts seemed to suggest Prevost will sell the entire manifold only.

If they won’t sell the parts you might have to go direct to a Norgren distributor or Norgren’s on line site.

[Corey]

Three weeks ago the valve and coil were available from Prevost. I just ordered both for a coach. They were about 30 bucks each give or take.

Mikee

[Billy]

I was able to just get the valve (641928) and solenoid (641929) by calling Prevost.