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Topic: Air Dryer keeps purging (Read 1837 times) previous topic - next topic

Air Dryer keeps purging

I recently installed a DQ6026 filter kit on my Haldex air dryer. After the install on a short trip I noticed that the purge valve was kind of pulsing out air. I looked on the haldex troubleshooting guide where it said to remove the line from the control port to the governor to see if the purge cycle stops. It did and initially it has no air flow from the governor but after a moment it starts dumping air through the hose from the governor. If I hook it back up it immediately purges. So I replaced the governor but that did not fix the problem. I took out the purge valve and cleaned it. That didn't help. The pressure builds to the correct level, haldex purges and it keeps purging air about every ten seconds. To me it sounds like the compressor just keeps pumping air. I talked to several people I know from the forum who think the problem is in the dryer. I ordered a DQ6020 major dryer kit from Napa that will be here tomorrow. I just don't understand how the dryer controls the compressor. I would think the governor is responsible for shutting it down at the set pressure. Can someone enlighten me as to how that all works? Thanks for any help.

Mark
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Mark and Tanya
Milton , Florida
US Navy Veteran (DV)
1999 U270 Special 40' CAI , 2015 Jeep Wrangler Sahara

Re: Air Dryer keeps purging

Reply #1 –
Quote from: MAZ –
The pressure builds to the correct level, haldex purges and it keeps purging air about every ten seconds. To me it sounds like the compressor just keeps pumping air.

Does anything in this thread help?  Air Compressor doesn't kick out after air dryer exhausts?
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Air Dryer keeps purging

Reply #2 –
Thanks Michelle.
    I did read that the other day but after reading it again I am hopeful that the rebuild kit will take care of it. I just didn't want to go through all the effort and find that the problem wasn't the dryer.

Mark

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Mark and Tanya
Milton , Florida
US Navy Veteran (DV)
1999 U270 Special 40' CAI , 2015 Jeep Wrangler Sahara

Re: Air Dryer keeps purging

Reply #3 –
Mark, When your rebuild the dryer take a real close look at the shuttle valve in the bottom of the dryer.  Any trash in this area will cause the purge valve to stick.  The valve itself is plastic or rubber and a B... to replace, probably have to have it on the bench to replace it.
Gary B

Re: Air Dryer keeps purging

Reply #4 –
Mark  ----  I just replaced my whole dryer, I decided that it was better to have a new one rebuilt by an expert.  It is not a real tough job.  You may want to look into putting a lubricant into the system also when and if you install a new one.  Actually, I think it was a rebuilt that I installed.  ----  Fritz
Fritz & Kathy Johnson
1991 36'

Re: Air Dryer keeps purging

Reply #5 –
I agree, factory reman is a very good choice, as it is a complete overhaul, not just filters.  Repeat, factory, as in the factory that originally built it, not someone using "probably will fit" parts.

Fritz, please explain your comment about lubricant.  Dryers are designed to REMOVE oil as well as moisture. Oil on the rubber components of your air suspension and air brakes are a NEGATIVE.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air Dryer keeps purging

Reply #6 –
Thanks everyone for your responses. Since I have the rebuild kit coming tomorrow I decided to dis-assemble the unit today. There really is nothing to these things. Just a few seals and valves. Should be a piece of cake to rebuild. Anyhow I think I have found my problem. The turbo saver valve is broken at the o-ring seat. See picture. It appears to be allowing air past it from the control port causing purge cycles. I will follow up tomorrow after rebuild. Thanks again everyone.

Mark
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Mark and Tanya
Milton , Florida
US Navy Veteran (DV)
1999 U270 Special 40' CAI , 2015 Jeep Wrangler Sahara

Re: Air Dryer keeps purging

Reply #7 –
Brett, When I rebuilt my dryer it came with a small cup of lube to be applied to the shuttle valve, looked like a thick Vaseline.
Gary B

Re: Air Dryer keeps purging

Reply #8 –
Thanks, Gary.  Makes perfect sense.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air Dryer keeps purging

Reply #9 –
Brett  ----  When I picked up my air dryer the parts man said I should (could) put some of this lubricant in the line to the sys. to help keep valves working well.  I was having some sticky valve issues which resulted in bleed down of the air pressure in irregular cycles.  I did that when I put the dryer in and it has improved the air bleeding issue.  I agree with what you have stated about oil in air systems as I have seen a 400 lb air pipe turn red from heat of combustion due to oil contamination.  I dont know what the lubricant is, but must be OK for air sys. or at least at this pressure.  Anyone thinking of doing this should check with the chassis manufacturer and see what they recommend.  My chassis is an Oshkosh, and I got my info from Freightliner who now owns Oshkosh.  I hope this clarifies things, and if I'm in error here please advise.  Thank you and I wonder if this should be done at some interval.  ----  Fritz
Fritz & Kathy Johnson
1991 36'

Re: Air Dryer keeps purging

Reply #10 –
Well I received the repair kit today and rebuilt the dryer. Very straight forward job. The new turbo saver valve was engineered a little bit better. Everything is working great now. Thanks everyone.

Regards, Mark
The selected media item is not currently available.
Mark and Tanya
Milton , Florida
US Navy Veteran (DV)
1999 U270 Special 40' CAI , 2015 Jeep Wrangler Sahara

Re: Air Dryer keeps purging

Reply #11 –
Brett  ----  More on the air dryer and air sys.  Talked with the Freightliner parts and service dep'ts and basically the stuff that is put into the air sys. is a conditioner as apposed to a lubricant.  It is mostly alcohol and used by OTR truckers to keep moisture out of the trailers they pull.  It can be used in MH chassis if used sparingly.  The parts dep't sells it, but the service dep't doesn't recommend it for MH use.  MH's just don't get enough driving time and the air sys. doesn't get that much air it.  The service man said that the little bit of moisture (about a tbl spoon) that I am getting from one receiver is not a problem.  He says to drain the receivers and watch for an increase in moisture up to about a cup full before you attack the air dryer.  These dryers are not that efficient and some amount of moisture will get thru.  OTR truckers go 60 to 70 thsnd miles before they replace the dryer element.  I replaced the original dryer in my 91 (which was not available anymore) with a Bendix AD-9 and filter elements are readily available for these.  That's my home work for today  ----  Thank you and have a great day  ----  Fritz
Fritz & Kathy Johnson
1991 36'

Re: Air Dryer keeps purging

Reply #12 –
Fritz,

Consider the Bendix AD-IP.  Easier to service and pretty much a direct replacement.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020
 

Re: Air Dryer keeps purging

Reply #13 –
We carry a can of 'air brake anti-freeze' after we froze up one winter time many years ago. We could not get our air pressure where it should be and pulled into a garage, where they poured anti-freeze into a disconnected governor line and we were good to go. Since then we carry the can, which I think is just alcohol. And we stay out of Ohio in winter.