engine103 Posted October 13, 2023 Share Posted October 13, 2023 Have noticed lately that my air dryer is not purging as it has in the past. I have listened for it as the compressor reaches operating pressure, nothing. Also have used an aux compressor to fill the system to 120 PSI, still nothing. Yes, the filters have not been changed in maybe three years. Could the pop-off valve be stuck? Could the filters be so clogged that it can cause it not to release? Jim Eastburn 2000 Signature Link to comment Share on other sites More sharing options...
96 EVO Posted October 13, 2023 Share Posted October 13, 2023 Well, you can forget about your compressor unloading / dryer purging, if you air up your tanks with a portable compressor! You have removed the engine compressor and air dryer from the picture! 1 Link to comment Share on other sites More sharing options...
engine103 Posted October 13, 2023 Author Share Posted October 13, 2023 Good morning, thanks Ben, I use the aux compressor to air up when I'm leaving the campsite early in the morning so as not to wake anyone. But even using the engine compressor the air dryer will not purge. Jim 2000 Signature Link to comment Share on other sites More sharing options...
96 EVO Posted October 13, 2023 Share Posted October 13, 2023 Does your tank gauges stop climbing at about 120psi? 1 Link to comment Share on other sites More sharing options...
engine103 Posted October 13, 2023 Author Share Posted October 13, 2023 Yes both needles actually maybe 125 or 130 PSI then drops to a steady 120. I drained the tanks this morning checking for water and they were free of any contaminates 1 Link to comment Share on other sites More sharing options...
Solution 96 EVO Posted October 13, 2023 Solution Share Posted October 13, 2023 Hmmm. So your governor is unloading your compressor, just no purge. You may be better off just replacing the dryer assembly. They do tend to fail after a while, and replacing them isn't much more than buying the rebuild kits. 1 Link to comment Share on other sites More sharing options...
engine103 Posted October 13, 2023 Author Share Posted October 13, 2023 Thanks Ben, I'm considering that option. Link to comment Share on other sites More sharing options...
Jdw12345 Posted October 13, 2023 Share Posted October 13, 2023 (edited) I would check the air governor for proper operation. I would replace the purge valve next, jmo. This might help. https://www.wabco-customercentre.com/catalog/docs/mm34_web.pdf Edited October 13, 2023 by Jdw12345 1 Link to comment Share on other sites More sharing options...
Romeo84 Posted October 13, 2023 Share Posted October 13, 2023 Went through this last year. The purge valve in the air dryer was old dirty and not sealing so it never fully seated. You can get a new purge valve kit for cheap it doesn't come with the slide valve though. I bought a new air dryer off Amazon that was defective so don't do that. If the needle stops building its in the dryer. 1 Link to comment Share on other sites More sharing options...
dennis.mcdonaugh Posted October 13, 2023 Share Posted October 13, 2023 Buy the upper and lower rebuild kit. They're easy to rebuild after you remove it from under the coach. 1 Link to comment Share on other sites More sharing options...
engine103 Posted October 14, 2023 Author Share Posted October 14, 2023 It might be easier to rebuild than it was to find it! 1 Link to comment Share on other sites More sharing options...
96 EVO Posted October 14, 2023 Share Posted October 14, 2023 1 minute ago, engine103 said: It might be easier to rebuild than it was to find it! Ha! Yeah, in those days they mounted them in a gawdawfull place for an RV! Fine for a semi where they were easily accessible with no trailer! 1 Link to comment Share on other sites More sharing options...
Paul J A Posted October 14, 2023 Share Posted October 14, 2023 Contamination of the air system in the coach would be my primary concern. Replace it. It MAY be 23 years old. 1 Link to comment Share on other sites More sharing options...
engine103 Posted October 14, 2023 Author Share Posted October 14, 2023 Paul, that may be true. Draining the holding tanks revealed no moisture or oily substance so I think I'm good there. But, your right, I'm not going anywhere for a while and plans are to replace it. Thanks, Jim On 10/13/2023 at 1:23 PM, Jdw12345 said: I would check the air governor for proper operation. I would replace the purge valve next, jmo. This might help. https://www.wabco-customercentre.com/catalog/docs/mm34_web.pdf jdw12345, thanks for the link, going into my file! Jim Link to comment Share on other sites More sharing options...
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