[Rongripon]

Gurus,

I have had a weird leveling related issue for a while.  One of the senior gurus reminded me that collecting data is a valid way of isolating problems and identifying the likely cause.  This post is to document the data collected on my coach.  I present a problem and an approach to troubleshoot but not an answer.  (Because I have not figured it out yet).  

In a nutshell, the issue is that if I leave the coach in travel mode at full travel height, the coach stays level and does not leak down.  However, If my air bags are somewhat below travel height, they will leak rapidly down in the rear of the coach.  (For example if I auto level, or turn tightly where the HCV has let air out on one side, ...).

I have attached a document with three graphs of data collected over the past couple of days....The coach was parked on a reasonably level pad.  Measurements were made at the bottom of the body panels behind front wheels and the bottom of the body panels in front of drive wheels.

Three tests were run:

No Auto Level (travel mode).  The coach was put into travel mode and measurements taken over a 36 hour period.  

Auto Level On -> Off .  The coach started at travel height, and was then auto leveled.  Auto level was then turned off and measurements taken after 2 hours.

Travel -> Dump Air (No Auto Level) -> Off .  The coach started at travel height.  Air was dumped using the leveling system for 8 seconds.  Then the HWH was turned off.  Measurement was taken after 4 hours.


Observations:  

1)  The coach does not leak much in level mode with the bags full.
2)  Auto-level results in the coach dropped in the rear.
3). If I partially deflate the bags using the dump valve, the coach will continue leaking down to the bottom.  (This is with the key off and with auto level turned off).   
4)  With the key off and auto level off, the coach should maintain its height, but does not. 
5) The leak appears to be in the rear air system.
6)  When the leak is present, both the left and right rear air bags seem to track each other.  
7)  The leak down is not related to the auto-re-level logic because auto level was turned off in each scenario.

Next steps....  
1) Adjust the mercury switch so that auto-level results in an initially level coach.  I will do this by using a 4 ft level to manually level the coach, then will zero out the mercury switch.
2)  Since the problem seems to be related to the amount of air in the bags, I will replace the HCVs.  My HCVs are original in the coach and I really just want to replace them for general purposes.  I will try the tests again with new HCVs.  In the meantime, I will use my isolation tool to try to isolate any leaks to the 6 pack solenoids or downstream air bags.
3) I will also repeat scenario 2 (partial air in bags) and see if I can detect a leak with my sonic leak detector.

Cheers,
bill

Hello Bill, I fought the same issue for a while but it was on the right side. I Have a Valid system and the 6 pack block is HWH. I disconnected the main input to the block and blew the block and line out. it helped and was able to get it to raise. it was like I had something caught in the system. we don't leave here for a week or so and I'll know it was fixed. fingers crossed.