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DaddyMc
Joined: 05 Feb 2006
Posts: 14
Location: Northern Ontario Canada
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| Posted: Tue Nov 07, 2006 11:23 am Post subject: air goes up, air goes down! |
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What would cause the pressure to fluctuate in the #2 tank as I am driving down the road (110-125psi). Air dryer is purging every 30-45 secs then pressure drops & builds.
Only while driving, not while spring brakes applied, no audible air leaks when shut down. Gauge only fluctuates while driving.
2001 Nav 9400i.
Was told the air dryer might need replacing or the governor. |
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Rev.Vassago
Joined: 04 Apr 2006
Posts: 5197
Location: Green Bay, WI
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| Posted: Tue Nov 07, 2006 11:26 am Post subject: |
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That would be my guess - either the air dryer or the compressor governor.
I've had trucks that have done that before - they seem to get "stuck" in a loop, and keep building up air, dumping it, and building it up again. Every time, it was either the dryer or the governor. |
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watevr777
Joined: 14 Nov 2005
Posts: 85
Location: Louisiana
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| Posted: Tue Nov 07, 2006 4:30 pm Post subject: |
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| rebuild your air dryer ...you should rebuild it every oct or nov of you run cold weather |
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COLT
Joined: 03 Jan 2006
Posts: 576
Location: FT ST JOHN
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| Posted: Tue Nov 07, 2006 5:09 pm Post subject: |
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| I've had the purge valve do that, right on the bottom of the air drier. I agree it's the time of year to replace the cartrige in your drier. The oil your compresor makes will plug the filter when it gets cold. (spell check is not working) :lol: |
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bob h
Joined: 15 Oct 2006
Posts: 664
Location: Nb
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| Posted: Tue Nov 07, 2006 5:35 pm Post subject: |
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watevr777 wrote: rebuild your air dryer ...you should rebuild it every oct or nov of you run cold weather
Every second year is lots IMO, unless you live in an area with unusually high humidity. |
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bob h
Joined: 15 Oct 2006
Posts: 664
Location: Nb
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| Posted: Tue Nov 07, 2006 5:39 pm Post subject: Re: air goes up, air goes down! |
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DaddyMc wrote: What would cause the pressure to fluctuate in the #2 tank as I am driving down the road (110-125psi). Air dryer is purging every 30-45 secs then pressure drops & builds.
Only while driving, not while spring brakes applied, no audible air leaks when shut down. Gauge only fluctuates while driving.
2001 Nav 9400i.
Was told the air dryer might need replacing or the governor.
Use a spray bottle with diluted liquid soap (or leak finder)... check for leaks ; a leaking reservoir signal line will cause compressor cycling... P.S. - this condition is DEATH for your air compressor... it's not designed for such a high duty cycle. |
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COLT
Joined: 03 Jan 2006
Posts: 576
Location: FT ST JOHN
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| Posted: Tue Nov 07, 2006 6:04 pm Post subject: |
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| Windex makes really good bubbles. :lol: |
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Jumbo
Joined: 27 Aug 2006
Posts: 726
Location: Northern Wisconsin
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| Posted: Thu Nov 09, 2006 7:52 pm Post subject: |
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| Just another suggestion. Could be the clutch fan leaking air. My bosses truck had same problem. Shut truck off and in two minutes all air was gone out of system. |
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DaddyMc
Joined: 05 Feb 2006
Posts: 14
Location: Northern Ontario Canada
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| Posted: Sat Nov 11, 2006 4:33 pm Post subject: |
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Jumbo wrote: Just another suggestion. Could be the clutch fan leaking air. My bosses truck had same problem. Shut truck off and in two minutes all air was gone out of system.
Bingo...I was told by the Shop Foreman that the line to the Fan T-stat was leaking. I had no idea that the air system had anything to do with the fan! I am a car hobbiest...so in my world the fan is powered electrically or by the engine using a thermo clutch.
I never looked under the hood for the problem, I have a garage to do that(I'd get in trouble for messing around with repairs...aka not qualified :lol:) I was just curious to know as the shop guys I talked to on the phone 2x thru my dispatch gave me vague answers as to the problem but told me it was safe to drive. I had to trust them, but in my eyes I wonder if I should have parked the truck (from air brake course --> air pressure loss over 3psi/min for tractor unit) :? Would "Johnny Law" have nailed me here? |
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xzostd1
Joined: 25 Mar 2006
Posts: 100
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| Posted: Sat Nov 11, 2006 5:14 pm Post subject: |
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COLT wrote: I've had the purge valve do that, right on the bottom of the air drier. I agree it's the time of year to replace the cartrige in your drier. The oil your compresor makes will plug the filter when it gets cold. (spell check is not working) :lol:
Spel watt? |
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