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Topic: 2003 U320 Major Air Leak Fixed - Culprit was dessicant (Read 861 times) previous topic - next topic

2003 U320 Major Air Leak Fixed - Culprit was dessicant

Aux compressor would only build to about 35psi (sometimes more, sometimes less). 

To help identify where the leak might be, I added shutoff valves to lines 57 and 75 on the compressor "Christmas tree" (see photo 1).  When I closed the valves, I still could not build pressure, indicating the problem was somewhere in the plumbing between the compressor output and the isolation valves.  By disconnecting various fittings and placing the pressure gauge ever farther from the compressor, I found that the culprit was the dessicant bowl.  I removed it (leaving the water separator immediately upstream in place) and found that I could build full pressure (approximately 100psi) (see photo 2).  Goodbye dessicant bowl!  Others have reported problems with this item, so I now join them.

I still have a small leakdown, but it is a minor issue.  I can now move on to more pressing items (meaning -
those items the wife wants done).
Jim McNeece
2003 U320 40'
2017 Chevy Colorado Tow

Re: 2003 U320 Major Air Leak Fixed - Culprit was dessicant

Reply #1 –
Must have been quite the leak ... never had the desiccant bowl leak, but have had other areas in there cause me leak problems.  Lots of quality time spent in that bay, and I bet you are not done (hint hint) :P

If you do not plan on replacing that, you could also go back to a HWH standard filter configuration as well. 

To do that you would move the very first filter on the outlet (the one with the solenoid valve on the bottom) to be the only filter in the system.  Basically moving the solenoid and stone filter from that and place it on the one attached to the pump.  Then take the pump output and go right to that filter.

Foretravel added the desiccant and then the second filter (its a finer one for the desiccant dust) downstream of it.  The HWH standard was simply the first filter, so pump, filter, outlet ... where as yours was pump filter desiccant filter outlet.

Have not done this myself since I like the "idea" of the desiccant, but thought I would offer it up since without the desiccant it in place, the extra filter is just extra connections, plumbing and leak points.
2000 / 36' / U320 / WTFE
WildEBeest / "Striving to put right what once went wrong"

Re: 2003 U320 Major Air Leak Fixed - Culprit was dessicant

Reply #2 –
Quote from: Steve –

Have not done this myself since I like the "idea" of the desiccant

I agree with my DH ;D  (shhhh... don't tell him.... I've got an image to uphold)

After staring at our air schematic, and if I'm following it correctly I'm guessing FT has the desiccant in the design because the aux compressor is also used for leveling (it looks like feeds the manifolds directly) and because it feeds the slide bladder tank directly - it's output doesn't go through the air dryer.

Of course, if I've misread the schematic, let me know. 

I would monitor the air tank bleeds for moisture if the desiccant bowl is eliminated from the aux compressor system.
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: 2003 U320 Major Air Leak Fixed - Culprit was dessicant

Reply #3 –
Quote from: Michelle –
After staring at our air schematic, and if I'm following it correctly I'm guessing FT has the desiccant in the design because the aux compressor is also used for leveling (it looks like feeds the manifolds directly) and because it feeds the slide bladder tank directly - it's output doesn't go through the air dryer.

Of course, if I've misread the schematic, let me know. 

You are reading it correctly. That is why they put in the desiccant on that compressor.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: 2003 U320 Major Air Leak Fixed - Culprit was dessicant

Reply #4 –
Quote from: indio192 –
Aux compressor would only build to about 35psi (sometimes more, sometimes less). 

To help identify where the leak might be, I added shutoff valves to lines 57 and 75 on the compressor "Christmas tree" (see photo 1). 
Jim, I have had several leaks on those shut off valves from HWH. I had to replace them with ball valves.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: 2003 U320 Major Air Leak Fixed - Culprit was dessicant

Reply #5 –
Our OLD (compared to you folk with slides) coach does not have a desiccant bowl on the 12V compressor. It does have a bowl that appears to trap and purge some moisture that the empty bowl captures. It does indeed supply compressed air to the air springs under some circumstances. However, it appears to me that air from the "big" compressor and associated dryer would serve to keep moisture out of the air suspension system.

For the bladders that seal slides, most of the air likely comes from the "big" compressor if the engine is left running during setup. However, inflation with the 12V could introduce moisture if there is not some kind of dryer. The bladders would not have significant amounts of dry air flowing through them. The air springs do have lots of dry air flowing through them while traveling.

Does that rationale for a dryer on the 12V compressor on "new" coaches make sense?
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: 2003 U320 Major Air Leak Fixed - Culprit was dessicant

Reply #6 –
Hi,

On my 2002, from it's placement I wonder if the desiccant is there only to filter the exhaust air from allowing moisture to foul the exhaust solenoid valve. Do other coaches have one in line with the air inlet to the auxiliary compressor?

Jim
Jim Frerichs
2002 U320 42'

Re: 2003 U320 Major Air Leak Fixed - Culprit was dessicant

Reply #8 –
Quote from: indio192 –
My basis for removing the dessicant bowl is found in this discussion thread:
Is the desiccant air dryer in line with the 12 v air compressor really needed?
Jim
I reviewed the thread referenced above. Our "old" system, that has no desiccant filter, will not pressurize the "main" (brake) system from the 12V compressor. The 12V system will only provide pressure to the air springs, as required, when the coach is parked. It appears that some of the newer coaches allows the 12V system to provide air to the system that provides pressure for brakes. You wouldn't want any moisture in those circuits.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX
 

Re: 2003 U320 Major Air Leak Fixed - Culprit was dessicant

Reply #9 –
J.D.,

I agree a 100% about not getting wet air into the brake air tanks.  That's why the "Air Tank" switch should be used judiciously.  If you are one of the few who keep their HWH air dryer maintained, you can use it any time.  However, most owners are not even aware the HWH dryer exists, much less that it needs frequent attention.  For those, the "Air Tank" switch should only be used in an emergency.

In my opinion, it was not the world's greatest idea to plumb the HWH aux compressor into the brake air tanks without clear warnings about the need to keep the air dryer maintained.  At least they put a valve on it so the user does have control over when it is used.
Jim McNeece
2003 U320 40'
2017 Chevy Colorado Tow