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Air leveling issue 2000 Series

I've been reading though all the air leveling (six pack) posts and haven't seen much on the control system.  I've gone through the HWH ml31043 2000 Series Air Leveling Service Manual for troubleshooting.  Also, I'm just running the aux compressor so I don't need to run the engine.  Last year I swapped out the compressor for the Air-Zenith OB2 which has a 100% duty cycle.  I've run it continuously for over 45 min at a time to pump up all the tanks while working the leveling issue, and other tasks.

My issue is that the coach right rear won't raise for auto leveling, or manually, below 70 psi in the tanks.  Above that it seems to work OK.  The other three corners raise fine at lower pressures with just the aux compressor running.  Right now it is more of a nuisance but I don't see how this is happening and I have to be more careful.  I took apart and cleaned both rear raise valves and also replaced the coil on the right rear valve. I went through all the troubleshooting in the HWH manual and all looked fine.  All the LEDs are happy, fuse is good, and good voltage at the solenoid.
 
 It responds fine in travel mode at lower pressures.  It doesn't seem likely that it is a control issue.  I get 13.2V at the solenoid and a strong coil response.  The symptoms are like it is a manifold issue but I can't see how that could be.  The other possibility could be a bad valve that is hanging up but I've seen the piston slide smoothly when I had it apart.  I didn't replace the piston. I just cleaned everything and reassembled with new o-rings.  The piston seat wasn't very worn. The bags hold air and vent fine.  Baring any other suggestions I may need to swap out the solenoid with a new one.  I'm not sure now a rebuild with new piston will fix this.
Andy & Sue (and Sofie dog) + Lucy dog
2002 U320 4020
# 5959
TOAD 2014 CRV

Re: Air leveling issue 2000 Series

Reply #1 –
Hello Andy,

First, let me compliment you on your thorough analysis of your problem, and on your logical trouble shooting efforts.  You obviously have a good understanding of how your air system is supposed to operate.  You are way ahead of many owners in this regard.

You DO have an interesting malfunction.  Since the "failure to raise" only occurs on one rear corner, it is hard to come up with a logical reason.  You might try some sort of "swapping" test to narrow down the area of concern.  For instance, you could try reversing the air lines that run from the 6-pack to the rear air bags.  Connect the right air bag supply line to the left raise solenoid, and vice versa.  See what happens?

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air leveling issue 2000 Series

Reply #2 –
I was hoping to not have to mess with the air lines.  I'll consider it though.
Andy & Sue (and Sofie dog) + Lucy dog
2002 U320 4020
# 5959
TOAD 2014 CRV

Re: Air leveling issue 2000 Series

Reply #3 –
Out of curiosity, does that side exhibit any signs of leakdown when the leveling system is off?  How does the piston seat look on the lower/dump solenoid valve for that side?
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Air leveling issue 2000 Series

Reply #4 –
No sign of leak down. After 24 hrs it's rock solid.  I did a leak check at the manifold and no leaks there.
Piston seat had slight dimple.  Still seems to seal well.
Andy & Sue (and Sofie dog) + Lucy dog
2002 U320 4020
# 5959
TOAD 2014 CRV

Re: Air leveling issue 2000 Series

Reply #5 –
Quote from: AdventureSofie –
No sign of leak down. After 24 hrs it's rock solid.  I did a leak check at the manifold and no leaks there.
Piston seat had slight dimple.  Still seems to seal well.

That would rule out a leak-through of the dump solenoid.  It's not like the raise or travel solenoids which can leak through internally and you wouldn't have external bubbles.

Quote from: Chuck & Jeannie –
You might try some sort of "swapping" test to narrow down the area of concern.  For instance, you could try reversing the air lines that run from the 6-pack to the rear air bags.  Connect the right air bag supply line to the left raise solenoid, and vice versa.  See what happens?

What about swapping the 2 solenoids rather than the air lines - see if the problem follows the solenoid?

I will say I'm a little surprised the rear will raise at all, even on one side, at lower pressures.  Both of our coaches have required greater pressure than 70 psi to lift the rear, especially the '03 given the weight of the slide, and we always had to start the main engine to have adequate pressure to raise the back any distance.

Don't forget that you also have the tag air bags that need to help lift the rear (note how much the coach squats with the tag dumped). 
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Air leveling issue 2000 Series

Reply #6 –
Quote from: Michelle –
What about swapping the 2 solenoids rather than the air lines - see if the problem follows the solenoid?
Yes, swapping the solenoids was my first thought...but Andy said he rebuilt both solenoids.  In the process of taking them apart, cleaning them, and reassembling them I figure he would have noticed any glaring difference or anomaly.  So that's when I thought of swapping the air lines.  I foresee two possible results of doing so:

1.  The problem remains exactly the same - right rear won't raise.

2.  The problem moves to the other side - left rear won't raise.

Either way, it will have narrowed down the list of possible "suspects".
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air leveling issue 2000 Series

Reply #7 –
I thought I would try leveling again. Dumped air in bags. At 90 psi everything worked as it should, although slowly.  I may have misspoke on the air pressure earlier.  I think it's fixed as it levels properly now. Replacing the failing solenoid coil seems to be the cure.  Thanks for the input from everyone.
Andy & Sue (and Sofie dog) + Lucy dog
2002 U320 4020
# 5959
TOAD 2014 CRV