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Old 06-04-2016, 07:53 PM   #11
Bus Nut
 
Join Date: May 2016
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Originally Posted by engelstad View Post
Ok, I turned off bus and the air release to reduce pressure when bus is turned off, does not come from the brass fitting that seems to release air a few times per minute when driving.

Also I put my finger on it for a few min to see if air pressure would build up and gauge didn't show pressure increase. When I took my finger off of it though the pressure did decrease. I am in rural Nebraska but I found auto parts store and replaced the air dryer. No change noted yet but barely drove it since then. Old air dryer was very gunked up though.

If the brass thing is dumping air, I was wondering if I could remove the wire going to it, but it doesn't seem to be connected with quick disconnect... ??
Air dryers are a fairly common failure item - in the last 7 years alone I believe I've had at least 2 replaced. Purge valves are a lower failure rate item, I cannot remember the last one I had replaced. The wire should plug in somewhere - if not on the valve itself, then maybe a foot or so into the wiring somewhere. Unplugging this wire most likely will *NOT* stop an air leak. It would be due to the valve being worn and/or gummed up.
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Old 06-04-2016, 09:40 PM   #12
Mini-Skoolie
 
Join Date: Sep 2015
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Chassis: TC2000 RE
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Thanks. So the air dryer filter replacement did not seem to help increase air pressure.

I did experiment where I manually held down the middle part of the brass fitting, where holding it down does not allow the air to be released as it is now releasing every 10sec or so at about 90psi. The result after about 2min at 2000 rpm is the pressure increases to 130psi.

So this is good but I fear if I replace this brass purging valve with plug, then the pressure might just keep on increasing to too high...

A bit more to add... over the last week or so the max pressure the bus could maintain has slowly decreased from about 125psi to about 85psi now. Also a few months ago, the issue was the opposite in that the pressure was too high, 150psi or so. All of the sudden in that case around 800niles into a trip, the pressure went to 125psi and stayed there, until about 10 days ago etc...

Suggestions? Thx!
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Old 06-04-2016, 09:52 PM   #13
Mini-Skoolie
 
Join Date: Sep 2015
Location: Albuquerque, NM
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Year: 1998
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Chassis: TC2000 RE
Engine: Cummins 8.3; Allison 3060R
Rated Cap: 66 passenger
Also FYI this brass valve that is bleeding off air every 15sec or so is near the top of an air tank, making me think it is not for auto water removal and more for maintaining pressure...
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Old 06-04-2016, 09:53 PM   #14
Mini-Skoolie
 
Join Date: Sep 2015
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Engine: Cummins 8.3; Allison 3060R
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I can email picture of this brass valve if it helps. I can't seem to attach to this post... my email is jonathan.d.engelstad at gmail.com
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Old 06-04-2016, 11:19 PM   #15
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......... With your air system building up to different pressures, especially over ~120 PSI, it makes me think the air pressure governor is giving problems. It should "cut in" around 100 or so, and "cut out" around 120. This should keep your system between 100-120 without cycling the compressor too much.

This valve on top of a tank won't do much (if anything) to purge moisture from the system, with that information it makes me think it's a pressure relief valve which should open around 140-150. It should never open, when it does it usually means the system is building too much air pressure (or the valve itself is failing; the springs in them can get weak).
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Old 06-05-2016, 11:04 AM   #16
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defiitely sounds like a pop off valve of some sort..

the governor should be cutting off the compressor at 120.. a which time you should geta quick "WOOSH " from your air dryer.. a valve any place else that is releasing air isnt really the norm... you may have an auto purge valve which is more unusual..

to post pice here open a free photoucket account, post the pic to photobucket.. then in photobucket go to library, and then click the thumbnail pic...

then when viewing your large pic.. go to the right and scroll down a bit.. click the 'IMG' link and it will copy the link to your pic to the clipboard..

then open a post reply here and paste that link.. we all can then view the picture in this forum..

-Christopher
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Old 06-05-2016, 12:02 PM   #17
Mini-Skoolie
 
Join Date: Sep 2015
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Chassis: TC2000 RE
Engine: Cummins 8.3; Allison 3060R
Rated Cap: 66 passenger
Disconnected the wire going to the brass fitting that has been dumping air at about 85 psi; no change, continues to dump air at low pressure.

Manually pushed the nipple button in the middle of the brass fitting while wife revved engine; pressure builds to 135 psi and holds. Thinking about getting a plug at a hardware store to replace brass fitting to prevent low air pressure bleed-off (until I am home and can replace brass fitting). I'm assuming the spring in the brass fitting is failing. What do you think?
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Old 06-05-2016, 12:45 PM   #18
Mini-Skoolie
 
Join Date: Sep 2015
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Rated Cap: 66 passenger
http://
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Old 06-05-2016, 12:47 PM   #19
Mini-Skoolie
 
Join Date: Sep 2015
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Chassis: TC2000 RE
Engine: Cummins 8.3; Allison 3060R
Rated Cap: 66 passenger
The brass part with nipple in middle is what is bleeding off pressure around 85psi...
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Old 06-05-2016, 01:18 PM   #20
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so the large air line comes in through the frame? where does the small black air line go to? an eaccessory or rear suspension?

it looks like a pressure pop-off valve.. and you say there are wires connected to the top of it?
-Christopher
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