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Topic: Renovation chain-reaction: air bags to leak? (Read 544 times) previous topic - next topic

Renovation chain-reaction: air bags to leak?

So we replaced the air suspension boots (all 8 of them) and the next morning my air pressure on the gauge was zero. First thought was (a) we have a leak, second thought was (b) the HWH leveling auxiliary compressor had coincidentally stopped functioning.
First actions were to mix up soapy water in spray bottle and go in search of a leaking connection.  No bubbles at any connections although I did find that the solenoid for the PacBrake was leaking.  That explained to me why the main supply tank would often be empty (engine not running) but the two service tanks would have air (thanks to check valves). Luckily for me two days later I got to drive right to the national office of Pacbrake and get the part I needed.  That will be going in this week-end, but does not answer the question as to why the air leveling system is not holding air - and/or why the auxiliary compressor is not kicking in - and maybe why the air gauge reads about 70 psi now with the vehicle up on safety blocks and the HWH turned off.  Lots of issues have emerged and I am not sure they are all related - just some of the weirdness of one renovation creating/leading to another problem. Ideas?

My mechanic talked to FT today and they suggested that the solenoids 'six packs' might be leaking. I sprayed the front one looking for leaks and found none but did not slither under to check the one one near the rear axle.  We will get the kit and see how that goes. 
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: Renovation chain-reaction: air bags to leak?

Reply #1 –
Did it hold air before you changed the air bags? If so it isn't the valves.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Renovation chain-reaction: air bags to leak?

Reply #2 –
The solenoid valves in the six pack do not always leak externally, so your leaks may be through the valve and you will not see the leak from the outside.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Renovation chain-reaction: air bags to leak?

Reply #3 –
They did hold reasonably well before we changed the air bags and the connections don't leak (or bubble). That is part of the mystery. (1) Did something get into the system when the connections were being changed? (2) Did the auxiliary 12V compressor 'coincidentally' quit working? (3) Is the pressure switch on the aux-compressor suddenly on the fritz? (4) Is there a leak elsewhere? I already found the one on the PacBrake system but that just draws down on the Supply/wet tank - and I believe that the service tanks up front are the ones that 'feed' the air suspension system.
I assume that the system works something like this (I am seeking correction on this, by the way) The leveling switch,  mounted horizontally under the coach, sends signals (30 minute intervals) (actually the HWH control module 'reads' the signal at that frequency) about the need for raising or lowering (one side or the other, one end or the other) and the solenoids then comply with the instruction until one of the three leveling arms attached to the frame signals 'stop' and the solenoid closes cutting off the draw-down on one set of bags or another.
The 'fill' function from the aux-compressor switches on (pressure switch on the compressor that monitors line pressure to the 'service' tanks) and tops up the pressure in the tanks rather than feeding directly to the assorted airbags. [I am guessing here and invite correction or affirmation that I am right about this]. I am surprised by the small diameter of the air line feeding from that compressor.  By the way, does anyone know of a device that permits monitoring how often and for how long the aux-compressor comes on?
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: Renovation chain-reaction: air bags to leak?

Reply #4 –
Not sure on your coach, but on mine the "leveling arms" you see under the coach are the ride height control valves used when in travel mode, which set ride height when driving. The HWH auto leveling system uses a mercury switch, or an electronic one of some type, to keep the coach in a level condition. The hwh computer send this "level" signal to the leveling valves in the 6 packs to send air to the airbags that need adjustment. When in travel mode, different valves are used that direct air through the 3 height control valve to keep the coach height dependant on load etc. My 12v. compressor is only used to fill air bags in leveling mode. The main compressor can also do this if engine is running. In a perfect situation the coach will level and will recheck if 30 min again to see if it is still level and nothing will happen.  In real life there is always some leak and the compressor will probably run to make up for it when releveling. Mine probably runs 5 or 6 minutes an hour. Your hand is a good monitor, if every time you check the 12v compressor the head is hot, it is probably running to much and your have a good leak.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Renovation chain-reaction: air bags to leak?

Reply #5 –
Hi, sounds like you have a simple leak at the bags most probably the lines going into brass fittings. Check here and the threads for the brass connectors going into bag tops. Using your comments as a guide this is my assumption.
JohnH
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Renovation chain-reaction: air bags to leak?

Reply #6 –
Quote from: jcus –
Not sure on your coach, but on mine the "leveling arms" you see under the coach are the ride height control valves used when in travel mode, which set ride height when driving. The HWH auto leveling system uses a mercury switch, or an electronic one of some type, to keep the coach in a level condition. ... My 12v. compressor is only used to fill air bags in leveling mode. The main compressor can also do this if engine is running.
So... the question remains, what factors are involved in the 12v compressor not coming on to do its job through the night (air pressure went from 120 at night to 0 in the morning? A leak is one thing - and I am on the search for it, but the coincidental failure of the HWH system (red 'on' light was on) to not maintain the pressure and thus the level - is still a puzzle.  This happened the night after the day we replaced the airbags.
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: Renovation chain-reaction: air bags to leak?

Reply #7 –
Also... if the 12V compressor has its own tank, then where is it? I always assumed that it fed into the service tanks.[Sometimes my 'learning curve' with this wee beasty we have owned for a year is pretty steep.]
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: Renovation chain-reaction: air bags to leak?

Reply #8 –
If your fenders are on it will be very difficult to check the fittings on the top of some of the air bags. I had the same problem after changing bags and used dish soap and water and found a leak on one of the 90's at the top of the forward right rear bag. You might do a double check on them. The front right bag is almost impossible to see you might have to use a mirror to check it.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Renovation chain-reaction: air bags to leak?

Reply #9 –
Quote from: Mike_Sandra_Lloyd –
Also... if the 12V compressor has its own tank, then where is it? I always assumed that it fed into the service tanks.[Sometimes my 'learning curve' with this wee beasty we have owned for a year is pretty steep.]
On your coach as is mine there is no separate air tank the 12v compressor fills the wet tank.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Renovation chain-reaction: air bags to leak?

Reply #10 –
Quote from: Mike_Sandra_Lloyd –
Also... if the 12V compressor has its own tank, then where is it? I always assumed that it fed into the service tanks.[Sometimes my 'learning curve' with this wee beasty we have owned for a year is pretty steep.]
First, tank dropping to 0 overnight indicates a good sized leak. Had a 97 that used the service tanks for leveling and 12 volt compressor would keep them full [ to 90 psi] for the leveling system. Think newer coaches may have separate tank fed from 12 volt compressor and from main tank, with a check valve to prevent main tank from bleeding down. If 12v compressor not coming on, need to check compressor operation, first fuses and breakers, second pressure switch, and if they are good, compressor itself.
Your coach schematics for air system should show you air path. Old engineering saying.
"If its broke, what is the last thing you did to it"
Try leveling coach then shut off hwh, if air pressure good in morning, this narrows down possibilites.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Renovation chain-reaction: air bags to leak?

Reply #11 –
Woody,

You are doing a lot of "guessing" about how your leveling system works.  This is not necessary, nor is it constructive.  In order to understand the leveling and suspension system, you must have a air system diagram for your coach, and the owner's manual for your leveling system.  If you do not have the manual for your leveling system, it is readily available online.  It would be worthwhile for you to follow the two links below, read through the material, and learn how the HWH 600 Series operates.

The answers to ALL of the questions you asked (in posts above) are found in these two manuals.

Once you understand the system, you will be better prepared to trouble shoot any problems that might crop up in the future.  ^.^d

The first link is to the 600 Series Service Manual (that is the one on your coach).  It includes a very helpful trouble shooting section.

The second link is to the HWH Air Leveling Systems Textbook.  This is a more generalized description of all the HWH leveling systems, but it has more detailed explanations and goes deeper into the operation of each part of the system.  Once you have digested this info, you will be a expert on HWH leveling, and you won't have to "guess" any more about what is going on.

https://www.hwhcorp.com/ml11148.pdf

http://www.hwhcorp.com/ml20635.pdf
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"