Air System Leakage

[Skip Y]

A while ago I posted a thread regarding system air loss (lose some pressure overnite), and thought it may be related to the air dryer. Well, replaced the dryer with no improvement. Recently was underneath air tanks and found leakage from the blowdown valves. Freightliner suggested spraying WD 40 up into valves to see if it would clear any debris that may be in valve. Tried once and seemed to reduce leakage rate - will do again and see if that's the answer (easier than replacing valves)

Skip Y
2010 Journey 40TD
Freightliner Maxuum, Cummins ISC
WIT 47083, FMCA F263635

[twinboat]

The air dryer is not under pressure with the engine off.
Once it purges, it and the lines coming from the compressor are no longer holding pressure.
There is a series of check valve after the dryer that holds back system pressure between the 3 tanks.

[Skip Y]

EEKS, let me clarify - the blowdown valves that are leaking are from the bottom of the 2 main air tanks. These are the 3 valves connected to the lanyards that we are supposed to pull every so often.

Skip Y
2010 Journey 40TD
WIT 47083, FMCA F263635

[jelag]

replace the valves... Find a local Fleet Pride store, or a NAPA HD parts store and you can find these valves on the shelf... Fleet Pride also has a on line store PDC that can help...
The key here... is that the inside of the tank will dump scale into the system... by removing the valve and running the compressor for 5 minutes will help blow out the loose pieces....

Hope this helps...

[Skip Y]

Thanks, jelag. Sounds like you've already replaced the valves. replacing makes sense, doesn't sound like a tuff job. Does sound like a job that will have to be repeated occasionally.

Skip Y
2010 Journey 40TD
WIT 47083, FMCA F263635

[Skip Y]

Just a quick follow-up. Thanks to Jelag's suggestion to blow the crud out, I soaked the valves with WD for a while, then aired-up the coach and blew each valve for a few moments, shifting the lever as I pushed it to clean out as much contact surface as possible (pushed valves directly rather than use the lanyards). The coach then had 55# pressure after 2-1/2 weeks. Not perfect, but much better than 0# after 2 days. Soaked them again and blew down again, and did not feel any air leakage. Will see how much good this does.

Skip Y

[FIRE UP]

Hmmmmm,
I'm gonna have to take a look at my "blow down" valves. (actually never heard them called that before). Ours can be parked with 120 in the system and, 24 hours later, maybe 60, maybe less. I've sprayed as many of the fittings and valves as I can see or find and, well, no leaks in any of them. But, it does seem to leak faster if it's not on the jacks. If I level it which means bags dumped and jacks are supporting the motorhome, it takes quite a bit longer, as in 2-3 days to get down to 60 after leveling it.
Scott

[Jon_C]

Scott my airbags were leaking id spray some soap solution on them especially where rubber makes the 180 bend. Taking the load off them seems like theyd leak slower as u describe too.

[FIRE UP]

Originally Posted by Jon_C

Scott my airbags were leaking id spray some soap solution on them especially where rubber makes the 180 bend. Taking the load off them seems like theyd leak slower as u describe too.

Jon_C,
Yeah, I'm gonna have to slither under the big girl and spray some soapy solution around those bags. But, one of the other posters says the air dryer does not have pressure on it when the engine is not running and or, when the compressor has finished its cycle. Well, mine does. I have Schrader valve on the lower part of mine and, it has a slight amount of air coming from it. I keep a cap on it but, I'm still getting some seepage from it.
Scott

[DeanM2]

About how long should my air pressure stay?


I think mine are close to zero PSI after 24 hours.

[gatorcq]

I thought those were the Drain Valves. That is the word used at Camp Freightliner Class. They are use to verify there is no moisture in the tanks. They are also used to Drain the system prior to working on it.