[Harry]

If you place your level low control in the manual position air that would ordinarily pass through the ride height valve, either to fill or exhaust is blocked.

If you have air escaping from ride height valves when in the manual position something is wrong. Has anyone replaced Norgren valves?

[Tim]

Jon, I have replaced one or two valves but not ride height.

Do you think it is back-feed from the 5-port valves? At max height the ride height valves would be in dump position so any air presented to them would exhaust

Any thoughts appreciated.

[Jim/Chris]

how old are your airbags? It could be the air leaks you are hearing are from cracks that open wider and wider as the bag(s) fill and extend. This is common with old bags.

when the ignition key to turned from ON to OFF, all coils in the 5 stack level low manifold are deenergized and close and the leveling system should stop doing anything. This should also happen when the left and/or right is nuetralized(energy removed). That is if everything is working as its designed. The air path between the airbags and the ride height valves is suppose to be closed at each rear 5 port/3 way Norgren.

It could be the 5 stack left and right armature valve sticking open(corrosion) and not closing letting signal air to the rear 5 port/3 way norgrens and as a result they are providing an air pathway between the air bags and the ride height valve.

or it could be the spool valve inside the rear 5 port/3 way Norgren sticking(corrosion) and allowing the errant air pathway from the bags to the ride height valve(s).

Liam, I emailed you a very useful virtual pdf file.

[Jeff]

Thanks so much for the PDF. I was having a hard time reading the legend on Jon’s paper on the site.

Airbags new in 2011 and mechanic says they look new. Air is absolutely coming from the ride height valve exhaust hose. Put a finger over it and noise goes away.

Your guess matches mine. 5-port is not fully closing and with key off the air is flowing backwards from the bags.

I am guessing that I hear it only at high height because the bag pressure is higher the taller the bags.

[Dan]

As Don says the 5 port Norgrens go to a “neutral” position with the key off. In that position air is locked in the air bags if the valve closes as it is supposed to.

However, before you assume it is a five port valve make a simple check and verify air is not leaking past any of the solenoid valves in the manifold in the steer compartment by cracking the fittings and listening for air. If the 5 port cannot return to neutral is is usually a crud build up in the valve usually associated with moisture having been in the system, but if the solenoid valves in the steer compartment are leaking and holding pressure in the 5 port actuator that could be preventing the 5 port from shutting off air flow.

The solenoid valves, when de-energized shut off air flow, but are supposed to exhaust air from the 3 and 5 port valves so no pressure on the 3 or 5 port remains, and if that (rare event) was to happen a new 5 port would act the same as the existing one.

[DON]

Jon thanks. Related to what you wrote – if I raised the coach, and then bled the tank air off by dumping the front and then pumping the breaks – would that be an alternate way to remove the manifold from suspicion? (rob it of supply air so it wouldn’t be able to actuate the rear 5-way?

[John]

Just reach in the steer compartment with the accessory system aired up, key off.

Crack each compression fitting on the outlet side of the solenoid valve manifold. No air should escape. If that is the case, as Don suggests it is highly likely a 5 port Norgren has a spool not shifting to the neutral position as it should and it is allowing air to pass through it.

The only time you should get air through any of the valves on the manifold is with the key on. And then not always depending on what function you have selected at the level low controls.

I think yours is the pure, unaltered Prevost system.

[Dick]

Liam, no need to pump the brake pressure down. Brake tanks/pressure has nothing to do with the leveling/aux system and the 5 stack manifold. The 5 stack is only for the airbags and has nothing to do with brakes. Norgren spool valves have nothing to do with brakes. You can dump the aux system and the brake tank pressure shouldn’t budge.

[Dick]

Thanks Jon and Don. Only reason I was asking about dumping Aux air vice cracking open lines is I am about to leave for HHI and “Do no harm” is first in mind.

right now, none of my symptoms impact drivability so I will wait till I get back before I put a wrench to anything. Touching fittings that haven’t seen a wrench in over 25 years makes me nervous.

Given the age of my coach, I might just follow Jon’s zero-out paper and do some valve replacement.

Thanks for all the help.