Jump to content

air system purging too much from the dryer


BIGDOG66

Recommended Posts

OK guys new here and now needing a little info. Got a 2000 mack 4 axle road tractor the other day going down the road it started purging every 7 seconds then quit for a few days then started back up. so replaced the governor didn't help so started looking into the air dryer and purge valve pulled it off and tore it down and the filter had come apart in the can cleaned everything up and first rebuilt the purge valve still same so replaced it got a little better but basically the same. only thing left is the unloader I think. litttle more info what it is doing is going down the road or sitting in the shop it will build pressure to 125 psi then purge but instead of closing off it will continue to leak air down until it gets to 110 psi then purge valve closes and starts building pressure again and starts the whole ordeal all over again any help would be appreciated

Thanks Scooter

PS I talked to a tech rep for the maker of the purge valve, when I disconnect the control line to dryer it stops purging so according to him the dryer is ok what else is there tried 2 governorssecuredownload.jpg

Edited by BIGDOG66
Link to comment
Share on other sites

thanks but that was checked too actually it was the unloader in the compressor got a rebuild kit ordered be in tomarrow

Midland compressor?

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

Link to comment
Share on other sites

  • 4 weeks later...

bendix compressor still having issues

have replaced the following componants

compressor

dryer

purge valve

governor

has no audible air leaks this even has the Mack techs in Richmond Va scratching their heads, I have replaced every major component and it stll wants to build up to 130 psi then purge until psi drops to 110 or so then the purge valve shuts off and the cycle repeats. one note if I pull the feed line from the governor to purge valve it will stop purging any ideas what going on with this? thanks for any input

Link to comment
Share on other sites

It still sounds like the check valve from the dryer to the tank. If it does not close off, air keeps leaking back from the tank out the unloader, until pressure drops then the unloader kicks back in. Does not sound like you have tried that one yet.

Link to comment
Share on other sites

I had the same problem with the AD9. On the side of the dryer there is a half inch plug, take it out. Inside you will see a plastic X shaped pin, take it out. There is a spring attached to it. on the other end should be a small O ring. Mine was gone. Replace this O ring . Problem solved. PS I couldn't find one so I made one. from a rubber washer.

Link to comment
Share on other sites

  • 2 years later...

I been driving a 2012 Cascadia for about 3 months now, and it leaks air out a thin air line (pressure release valve?) under the motor every 10 to 15 seconds. Wasn't doing it until a few days ago. Company shop says it's normal. They claim to have serviced it with a kit of some sort anyway (doubt it). It got louder, so I called maintenance dept. and they didn't seem to think it was an issue. WTF? I know the damn compressor's got to be overworking itself. It doesn't "woosh" like it's supposed to, it just bleeds out the governor or whatever that line is. Anyway, sounds like the same thing this guy is talking about. I've read some stories online, and haven't really found a real solution. Doesn't seem like the problem ever gets fixed, or maybe it isn't a problem, but rather a condition in with some air dryers decide to work under out of the blue.

I know what started it with mine though. I hooked to this trailer the other day, and immediately after, this started going on. So i checked to see if there was a blow out valve (or air release valve) on the air tank under the trailer, and it was, I bleed it for a good couple minutes while it blew water and rust. So that got into the trucks air system for sure, as the tank on it bleeds rust residue now sometimes. I also tried plugging the little air vent line where the thing keeps purging the air out of for a sec and water started draining out the bottom of the air dryer, so i quickly unplugged the line before i fucked it up. Didn't have a clue what I was doing, but there was a thread online that recommended something similar to force the diaphragm to the blow off valve to close or whatever.

Just giving my story for the record. Going to have a company shop look at it again when they route me past one again. I don't care what they say, it ain't supposed to be doing that. It's just too loud, and there's got to be a reason why it doesn't "whoosh" like all the other trucks do.

The mechanic and the guy at the office both say it's supposed to purge after it gets to 125 psi. Well no fuckin' shit, but why would the compressor constantly be running when the tanks are full, or why would it keep cycling?

Edited by ProStarBrakes
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...