[tumbo1]

have had several problems with the air dryer on my 04 columbia replaced whole sysem twice and it started to leak air again so i got sick of it and just took the two lines going into it and put them together and bypassed the air dryer now everything works great will this be ok as long as i keep draing my air tanks to get the water out.

[allan5oh]

No, it still won't be ok. The air dryer gets rid of moisture in the air, draining your tanks won't do anything to the moisture that's already in the air.

Sounds like a purge valve problem, or the valves on your air compressor. Where does it leak from? I'd work on fixing the problem, rigging it like this is just asking for trouble.

[bob h]

Originally Posted by tumbo1

have had several problems with the air dryer on my 04 columbia replaced whole sysem twice and it started to leak air again so i got sick of it and just took the two lines going into it and put them together and bypassed the air dryer now everything works great will this be ok as long as i keep draing my air tanks to get the water out.

NO, get a competent mechanic to repair the problem. if your purge valve is having repeat failures, i would recommend an air compressor blow-by test

besides moisture, the dryer also removes oil vapour which causes damage/swelling to air valve seals

what exactly are you referring to as the whole system?

[tumbo1]

it leaks from the block that u screw the air dryer cartridge into one of the valves under there there are 2 it is the one in front did older trucks have air dryers on them i dont remember my old truck having one just sick of replacing parts on the air dryer have had it replaced 2 times in one year.

[JoeyB]

IF I understand this- you build air to the cut off, shut the truck off and walk around and hear the dryer leaking. If that's the situation, then the problem isn't the air dryer. The wet tank check valve is leaking. That allows air that is already in the tank to sneak back to the air dryer and exit out of the dryer's purge valve, which should be open any time the compressor is unloaded.

By all means, I would keep the dryer in the system. It's true, we didn't have them until the '70s or so, but brake pneumatics were so much simpler then, and even at that, it was not unusual to freeze up in cold weather. With anti-skid, and all the rest of it, I'd definately do whatever I could to protect that air system, cause once it's contaminated, I have no idea how to clean it.

[bob h]

Originally Posted by JoeyB

IF I understand this- you build air to the cut off, shut the truck off and walk around and hear the dryer leaking. If that's the situation, then the problem isn't the air dryer. The wet tank check valve is leaking. That allows air that is already in the tank to sneak back to the air dryer and exit out of the dryer's purge valve, which should be open any time the compressor is unloaded.

By all means, I would keep the dryer in the system. It's true, we didn't have them until the '70s or so, but brake pneumatics were so much simpler then, and even at that, it was not unusual to freeze up in cold weather. With anti-skid, and all the rest of it, I'd definately do whatever I could to protect that air system, cause once it's contaminated, I have no idea how to clean it.

not sure of the make of this dryer, but most bendix dryers used a check valve as their outlet port (to the wet tank). although, this is not the only cause of an air dryer leak; the purge valve uses air pressure against a piston to hold it's exhaust port open, and again the cut-off valve can leak out the purge valve... the cut-off valve is integral to the purge valve.

[tumbo1]

it is not only when the tanks are at the cutoff it is any time there is air in the tanks if i put my hand over that valve on the air dryer it stops leaking. i had to bypass it just to get it home because it would not hold over 50 psi but once i bypassed it it was fine held about 125 and built up right away.

[bob h]

Originally Posted by tumbo1

it is not only when the tanks are at the cutoff it is any time there is air in the tanks if i put my hand over that valve on the air dryer it stops leaking. i had to bypass it just to get it home because it would not hold over 50 psi but once i bypassed it it was fine held about 125 and built up right away.

purge valve

can you buy a separate purge valve for this dryer?

when you drain the tanks, do you have lots of water? how 'bout oil?

[JoeyB]

What bothers me about this is that he's on his 3rd dryer. That's why I went looking elswhere for the problem.

[tumbo1]

no water comes out i checked the tanks and th valves on the tanks they look in good shape and i could hear no leaking the truck is an o4 so everything is in good shape yet i called freightliner and can buy the whole air dryer system for 287 so i am picking it up today and putting it in i will post once i am done thanks for all the help