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Topic: Leak at Service Air Hose Valve (Read 410 times) previous topic - next topic

Leak at Service Air Hose Valve

So, I get ready to shove off today, and I needed to adjust my Tire Pressures, for extra weight I took onboard.  When I went into the bay, I heard a "Hiss", and Immediately knew I was in for at least another day, here! So, I called NAC, and didn't receive a call back, but researched the issue here, and found only one article from 6 years ago which could have been relevant, and found Conflicting Info.  My Dash gauge stayed up in the 100 PSI range for quite a while even though I started to disassemble the Water Hose Bib Style, 1/4" Shutoff valve to bleed the air off to remove it! I could not get the Handle off (Phillips) but will try again using a ratchet, 90 degree, to get more torque on it!  The First Jamnut was easily removed, but the Valve Body Jamnut was close to stripping, so I left it!  It will have to have the Stem removed, to come off! If I could get that off and take it to Home Depot, a simple repacking kit would work, as well!


Anyway, in the post it was said that that air for the Service Hose, comes from the Compressor to the first tank, then with a Check Valve to the Air Brake Tanks, 2 of them?  I do realize that a small leak is troublesome, but here it is 5 Hours later, and the Pressures went from 120 PSI, to 85 PSI on the White needle, and 50 PSI on the Orange needle.in the static (Engine Off) mode!

So, would it be safe to assume I can get on the road?  There is No Air Whatsoever left in the Service hose, I bled that off 10 minutes into the job!  I stopped there,  to Await the Factory answer.  So in the same post, people were talking about having a Double Male Quick Connect Fitting,  to pump their coach up by an external Compressor, to 120 PSI. If there truly is Possible, that conflicts with a Poster saying there is Check Valves between tanks?  Not having a Schematic puts me at a Standstill, as I am unsure if it is safe or not, at this point?  I'd prefer to have a Pro mess it up, and fix it, as if I start stripping things, matters will be worse, of course!

The Valve itself will be a Bear to Remove, as it is Mounted so close to the Top, Left Hand Corner of the Bay itself! I fear that since Everything, which involves 3 Connections, I end up Stripping one of the nuts...then it's Mobile RV Repair time!  Big Bucks, and loss of time here! Please advise, and anyone has a Link to the Pneumatics Schematic, that would be great.  The Manual gives a Description and Operation, but not Locations for all the Parts, and how they can be worked on, etc.

Here is the Post I was referring to!
Low Air Pressure from Air Hose
Tom & Barb Root
'95, 40' U-320C SE, bought from Dave Head, 8/2017  FT Motorcade # 18196 Coach Build# 4663 October '94
2015 VW Golf Sportwagen, 1991 Suzuki Samurai, Off-Road Custom Build-Up, W/Toyota 22re mill, and a 2005 Chevy 2500HD, Duramax/Allison TOADS Will also pull a MacGregor 26X Powersailor 2001 Model, owned since new!

Retired SR Rocket Mechanic, FT Sales Associate @  FT of California, Escondido CA.!  and Retired USMC Gunnery Sergeant (Hence Retired Guns! ) Avionics Tech, on A6E Intruder & OV-10 Bronco Aircraft!  V/N Era Vet, and Desert Storm Participant.  Happily Retired now!

Re: Leak at Service Air Hose Valve

Reply #1 –
Can you post a picture? Not sure which valve you are referring to. Air it up and see how fast it drops to 60, that's when the maxi starts applying the brakes.
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: Leak at Service Air Hose Valve

Reply #2 –
If you still have brake pressure after 5 hours, startup and go.
Steve DeLange
2005 U320T 40'
Pearland, Texas

Re: Leak at Service Air Hose Valve

Reply #3 –
I think DOT allows 2 psi per Minute leakage with engine off. My coach under way has an wide open 1/8" diameter air port called a vacuum generator that blows air all the time by design.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Leak at Service Air Hose Valve

Reply #4 –
OK, I went out, and before I really dug into it, making it worse, I bought a Tap and Die set, and chased the threads!  Evidently it was leaking all along, I just never caught it, because of the engine running?  It seemed like the threads were squirrely when I took the outer Jam nut off, and so I tried after I posted an confirmed it was Cross Threaded, but not too bad?  I never touched that area, so it could have been either loose, and by opening and closing the valve just popped on enough to allow just some air to come out!  When I shut the valve it did slow the leak a bit though!

Good to go , off to Vegas Tomorrow, from Santa Barbara, County!  It's now been, 7.5 Months in California, eastbound, finally!

I tried posting pics but did not figure out just how to do it?  I will not pay for a Hosting Site, and Drag and Drop just didn't work!  The Service Air is in the same bay, Passenger  side, with the Diesel Tank and LP Tanks! Upper left Hand (Rear) corner of the bay Just enough hose to reach the farthest point, being the Drivers Side rear Tires!

Still would like a Complete diagram and explanation of the whole system, and how it works, parts in it, etc. though!
Tom & Barb Root
'95, 40' U-320C SE, bought from Dave Head, 8/2017  FT Motorcade # 18196 Coach Build# 4663 October '94
2015 VW Golf Sportwagen, 1991 Suzuki Samurai, Off-Road Custom Build-Up, W/Toyota 22re mill, and a 2005 Chevy 2500HD, Duramax/Allison TOADS Will also pull a MacGregor 26X Powersailor 2001 Model, owned since new!

Retired SR Rocket Mechanic, FT Sales Associate @  FT of California, Escondido CA.!  and Retired USMC Gunnery Sergeant (Hence Retired Guns! ) Avionics Tech, on A6E Intruder & OV-10 Bronco Aircraft!  V/N Era Vet, and Desert Storm Participant.  Happily Retired now!