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Semi is dumping air out of the bendix air drier and can't figure it out.
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Hayinhere
Posted 10/8/2011 16:59 (#1995682)
Subject: Semi is dumping air out of the bendix air drier and can't figure it out.


Central NE

My KW T600 leaks air out of the bottom of the reciever drier.  I replaced the drier, and thought that solved the problem, but only for a day.  Then leak developed behind dash and I replaced the red supply valve.  I thought that solved my problems.  Now it's back to leaking out the bottom of the drier again.  I also replaced the Governor on top of the air compressor but the drier still leaks air.

When you start the truck, air builds to 120 psi no problem and no leaks.  When you push the brake pedal several times until the compressor kicks in at about 90 or 100psi, the air from the compressor starts comming out the bottom of the drier instead of charging the tanks.

What is going on?  both the old drier and the brand new one are discharging in the same way.???



Edited by Hayinhere 10/8/2011 18:31
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DR J
Posted 10/8/2011 17:05 (#1995688 - in reply to #1995682)
Subject: Re: Semi is dumping air out of the reciever/drier and can't figure it out.


South central Ks.
05 pete just started doing the same thing. Haven't had time yet to look at it. I will be interested in the reply's that you get.
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1820-10
Posted 10/8/2011 17:25 (#1995707 - in reply to #1995682)
Subject: Re: Semi is dumping air out of the reciever/drier and can't figure it out.


se montana
think you are asking sbout the air system ? dryer ? not reciever/dryer as in a.c. system? the dryer needs to be serviced as valve sticking open and doesn't charge air tanks. or needs to be replaced totally to a new dryer. we have had to do that to ours
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KevinM
Posted 10/8/2011 18:20 (#1995736 - in reply to #1995682)
Subject: Re: Semi is dumping air out of the reciever/drier and can't figure it out.



Did you just replace the cartridge or the whole dryer? Either way it sounds like the valve in the dryer housing needs replaced. There is a kit for that.
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Hayinhere
Posted 10/8/2011 18:22 (#1995740 - in reply to #1995707)
Subject: Re: Semi is dumping air out of the reciever/drier and can't figure it out.


Central NE

Yes, air drier not air conditioner.  This bendix drier is brand new (less than 200 miles on it) and is doing the same as the old one.

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Hayinhere
Posted 10/8/2011 18:26 (#1995745 - in reply to #1995736)
Subject: Re: Semi is dumping air out of the reciever/drier and can't figure it out.


Central NE

replaced the whole thing.  The old one hadn't ever been changed that I know of and when I disassembled it to try to figure out what was wrong, I noticed that a solder had broke loose on a heating element underneath also I couldn't get the cartrige loose so I replaced the whole thing.


Why does the valve not leak air when initially charging to 120, but does so when the compressor tries to re-charge? 



Edited by Hayinhere 10/8/2011 18:28
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JD fanatic
Posted 10/8/2011 18:39 (#1995757 - in reply to #1995682)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


mw
When was the last time you drained your air tanks? Too much moisture can cause things to get gummed up.. Maybe not the issue, but just a shot in the dark.
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glensts
Posted 10/8/2011 18:46 (#1995763 - in reply to #1995682)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.



Check your governor! When your governor hits 125 psi it purges to the air dryer to allow it to blow out moisture. The governor could be sticking on purge cycle allowing the air from governor to come out the dryer. Smack the governor and see if it'll quit.
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milofarmer1
Posted 10/8/2011 18:52 (#1995767 - in reply to #1995682)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.



Farwell, TX/Pleasant Hill, NM
Just tossing this out there, even though you changed the air governor it may still not be working right. I have seen brand new ones not work right (slow to kick in, hanging, etc). But later they start working right. It almost seems to me like they need to 'break in'. If it will eventually start building air, and is driveable I would try driving it for a while to see if it gets it's act together.

The last governor I changed the old one would hang on the pump cycle and would overpressure the system. The new one did just what you are talking about, build air until cut-out then would be slow to kick back in. The air pressure might get all the way down to 60 before it would pump again. It did that quite a bit at first, but like I said after a couple weeks driving off and on it works fine now.

Edit: while I was typing I see Glen had the same idea.

Edited by milofarmer1 10/8/2011 18:53
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tommyw-5088
Posted 10/8/2011 18:54 (#1995768 - in reply to #1995763)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


Central Texas
glensts - 10/8/2011 18:46

Check your governor! When your governor hits 125 psi it purges to the air dryer to allow it to blow out moisture. The governor could be sticking on purge cycle allowing the air from governor to come out the dryer. Smack the governor and see if it'll quit.



I agree ,could also be the 1/4" line to the drier from govenor .
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redgreenandrust
Posted 10/8/2011 19:18 (#1995785 - in reply to #1995767)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


thumb of michigan
i had the same problem, and oddly enough it turned out to be a brake chamber with a hole in the pancake.
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c2gleaner
Posted 10/8/2011 19:41 (#1995799 - in reply to #1995682)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


S.E. IL
pull the 1/4" inch line from the governer if it has a continuos flow of air then it's a governer problem. You can try plugging the 1/4" inch line and see if the governer is working by pumping the air pressure down with the pedal and watching the gauge. If pressure stops at 125 psi or so then the governer is fine if not the pressure relieve valve will "pop off" at 150-175 psi. If memory serves me right some governers have two 1/4" holes in them if so try switching to the other hole.
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KevinM
Posted 10/8/2011 20:14 (#1995830 - in reply to #1995745)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.



New or reman? Does it matter if all buttons are out or in? What brand and model of dryer?
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wall
Posted 10/8/2011 21:35 (#1995944 - in reply to #1995682)
Subject: RE: Semi is dumping air out of the bendix air drier and can't figure it out.


purge valve leaking?
http://www.beamalarm.com/foretravel-links/PDF/air_dryer_ad-9_instal...
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Offroadnt
Posted 10/8/2011 22:31 (#1996071 - in reply to #1995944)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


Southern Alberta Canada
That looks like good manual, I was thinking unloaders not working properly in compressor.
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Hayinhere
Posted 10/8/2011 23:42 (#1996164 - in reply to #1995785)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


Central NE

Interesting.  Do you know an easy way to go about checking for that?

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RiverRat
Posted 10/9/2011 00:04 (#1996198 - in reply to #1995682)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


northeast mo shelbina
had the same thing happen to mine one time, think it started with a bad governor, so I replaced it and did not get the plugs in the right places and would do the same thing yours is doing,so I took it back off compared the new with the old one and put the plugs in the same places , fixed it . something to check maybe ?
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mcupps
Posted 10/9/2011 00:19 (#1996217 - in reply to #1995682)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


Downtown Shell Knob MO Come Visit!
Take the sock off your foot, cut a piece off about the size of your hand then put it over the discharge of the air dryer and black tap or hose clamp it on. It will then let air escape as normal but build enough pressure to shut the diaphram on the air dryer "pop-off" valve. Not exactly DOT legal. But works if your in BFE with no airpressure and tired of getting out every 10 seconds and hitting the bottom of the dryer with a hammer.
I won't lie, Ive had at least 3 trucks with a piece of my sock over the pop off valve on the dryer at one time. I have a T600 that has had a sock on it for 4 years now. Everything else on the air system works correctly It works perfect. Except for it makes a little of a wistle sound as the air escapes the popoff valve. I did this after I replaced the dryer and the new one did the same thing within 6 months. Right now the motto is "don't fix it if it isn't broke"
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mcupps
Posted 10/9/2011 00:23 (#1996223 - in reply to #1996164)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


Downtown Shell Knob MO Come Visit!
You will know if you have a blow pancake because it will lose airpressure when you push the yellow button and release the maxi's plus you will be able to here/feel air coming from one of the brake pods.
I assume your air is escaping from the bottom of the air dryer. It will build air pressure normally, then it will pry to popoff but then you can hear air continue to come out in the push-push push push push push push push mannor, until it finally fades off to a slight little stream of air as air pressure gets closer to zero.
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Hayinhere
Posted 10/9/2011 00:42 (#1996236 - in reply to #1996223)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


Central NE

It pops off just fine.  no loss of air pressure until it kicks back on and tries to build air again, then only leaks air coming from compressor sh sh sh sh...sound.  The air supply in tanks does not change and holds steady unless I press brake pedal or use air for something.

I had a problem with trailer brakes one time that had me flustered that turned out to be a bad ABS valve that backfed compressed air through the blue line to the brake chambers on one axle.  That had me as confused as this does.

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mcupps
Posted 10/9/2011 00:52 (#1996247 - in reply to #1995830)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


Downtown Shell Knob MO Come Visit!
Your probably only holding pressure in the tanks because of a saftey backflow valve, just past the air dryer, othewise it would probably try to drain the tanks too. Youve got me on this one though. Have your tryed holding your hand over the popoff valve to build pressure against the diafram and see if it goes ahead and builds pressure as normal or like the first time. If so, its probably a bad popoff valve, if not, Its probably governor related.
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tlupton
Posted 10/9/2011 12:41 (#1996743 - in reply to #1996217)
Subject: Re: Semi is dumping air out of the bendix air drier and can't figure it out.


Oxford County Ontario
If you've done the air dryer and govenor the only thinks it can be is a weeping signal line from govenor to compressor or the unloader valves in the compressor. I would say that it is the unloader valves being that it only acts up after the compressor starts to warm up ( heat makes expansion, orings no longer sealing) what motor is in the truck and what year is it
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Hayinhere
Posted 10/17/2011 19:23 (#2008016 - in reply to #1995682)
Subject: RE: Finally figured it out


Central NE

Thanks for all the replys and help.  I posted the answer in a new post: http://talk.newagtalk.com/forums/thread-view.asp?tid=262236&posts=4#M2007518

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