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No Air in Rear Suspension
My coach will not air up in the rear. The front properly achieves ride height. I have confirmed that the level control rods are attached on both sides. Currently, I cannot safely block the bus up to manually test the leveling valves.
Air gauges on the dash indicate normal levels of pressure. Level low will raise bus. I am not sure if the rear bags will hold pressure for an extended period of time, but I can raise each side in the rear with Level Low. There are no audible air leaks in the steer compartment or at the rear of the coach.
I am scheduled to be at Marathon East today. My plan is to raise the bus manually via level low and make the trip (about 70 miles). I will stop periodically to check rear suspension. My bus is driveable with no air in rear, but the drive shaft angle to the rear end is concerning.
Any ideas or advice?
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8 Replies
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Colt,what happens when you raise the rear with level low, then switch to road mode? Also after raising and letting it sit (engine and compressor off) how quickly does the rear bags leak down? Did you check that the tags are not raised?
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Colt,
I have a guess and it is something you can check quickly.
Use level low and lower the front. Then go to the driving position and see if anything comes up. The two rear suspensions are independent of one another except for a shared air supply that is controlled to an extent by the center solenoid valve on the 5 valve manifold.
If nothing comes up (my guess) try switching the center solenoid valve coil with any other in the stack such as the bottom one.
If that does not work let us know.
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Jon, wouldnt the leven low system energize the proper solends to raise the rear? Colt mentioned that the rear came up on lever low, which would mean the solenoid is opening the valve.
Of course I’m going based on the liberty system and not really sure how marathon is setup.
If the coach can rise with level low, and switching to ride drops it,would that be the ride height circuit be in question, verses the valves/solenoids?
I know every once in a while, solenoids act up and switching between ride, auto and manuals helps “free” things up. I’ve also seen humidity in the system where the air dryer doesn’t keep up with it cause problems, requiring replacements of valves and filters (and draining tanks). Florida seems to be a great environment for this, especially as rain season and spring/summer kick in.
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Center valve/coil on the 5 port stack like Jon said.
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Charles,
The reason I am thinking the center solenoid valve is the issue is he said the rear will not rise. It is the only thing I can think of common to both sides.
If he uses level low to raise the rear he is sending air to the air bags through a different path. I suspect the front is not going to the road height either but it might not be down or it might not seem too low for driving.
The Liberty modifications really do not alter the basic functioning of the level low system and in fact either does the HWH. Those converter installed modifications just automate leveling.
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Okay, I always thought the level low (as on my liberty) was using the 5 port block/valves to manually raise/lower the front and rear sides. Since colt was saying that the level low switches raised the rear, it confused me why it would be the center port if the manual switches worked.
So back to one of Colts questions on using the manual mode to raise the coach to a height to drive in, my understanding is that it can be used to move the coach if the airbags are holding pressure.
If I was unable to bring the coach to ride height using the road mode, I would manually raise it up with the manual settings, confirm it’s holding pressure and if it is, move it to a place to get it serviced (in a reasonable distance).
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The five port Norgrens are the key, but when the pneumatic signal from the center solenoid is received by the 5 port valves the spool shifts to send air regulated via the ride height valves. When in manual mode the spool shifts in the opposite direction and then air is introduced or depleted by means of the buttons for each of the individual locations such as left rear or front.
In all cases the five port valves are in the air flow path, but they function to send air to the air bags either manually or via ride height valves.
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Charles, Jon and Tom:
Thank you for the help. I made it to Marathon without incident.
Interestingly, after raising the rear via Level Low, the coach, while parked, maintained height for 24 hours. I am not sure that the height was normal ride height, but the bags definitely held air, and I elected to try to make the trip to Marathon.
I checked the height several times on my trip. The coach appeared to be holding height. At least it was off of the bump stops.
I am thinking the cause of my “no air” problem was a temporary malfuction of either the solenoid or the Norgren. Either way, I have asked Marathon to address it.
Thanks again for the great suggestions. I appreciate this site and the helpful people who are on it; and Jon, thank you for writing and posting the article on Prevost air systems…the information helped me focus on the likely cause of my problem.
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