Author Topic: Air pressure trouble  (Read 377 times)

Online hogi6123

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Air pressure trouble
« on: May 05, 2021, 01:04:40 PM »
I took my bus out for a ride.  It was working fine.  I shut it off, 20 mi from home, now it starts, pressure is holding but doesn't build.  No air leak sounds from underneath.  8v92t manual.  Any suggestions?
1981 MC-9
1994 102DL3 (parts bus)
Central IL

Offline buswarrior

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Re: Air pressure trouble
« Reply #1 on: May 05, 2021, 02:46:31 PM »
Agitate with vigour, both brake systems, parking and service.

Something hopefully stuck half way between seated and unseated

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area

Offline chessie4905

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Re: Air pressure trouble
« Reply #2 on: May 05, 2021, 02:59:58 PM »
Try tapping air compressor governor.
GMC h8h 649#028 (4905)
Pennsylvania-central

Online hogi6123

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Re: Air pressure trouble
« Reply #3 on: May 05, 2021, 03:21:47 PM »
I tried draining all air tanks and restarting the engine.  And tapped on the governor best I could.  I walked to the nearest hardware store and bought a small 110vac compressor.  Now pumping up...

I will have to service my governor and compressor before my next trip.
1981 MC-9
1994 102DL3 (parts bus)
Central IL

Online hogi6123

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Re: Air pressure trouble
« Reply #4 on: May 05, 2021, 03:45:58 PM »
The compressor I got will take several hours  :'(  If my wife had stayed home she could have brought me a bigger one.
1981 MC-9
1994 102DL3 (parts bus)
Central IL

Online hogi6123

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Re: Air pressure trouble
« Reply #5 on: May 05, 2021, 06:30:43 PM »
The little compressor couldn't handle the whole bus, so after a loong time trying, to actually get out of there, I moved the compressor to the emergency brake fill and pumped that to 120 psi.  The parking brake released (one full application of service brakes needed) and then I drove the bus home without using the brakes, so I wouldn't get stuck somewhere in the middle of the road.   Sigh... my first disabled bus experience.  :P
1981 MC-9
1994 102DL3 (parts bus)
Central IL

Offline chessie4905

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GMC h8h 649#028 (4905)
Pennsylvania-central

Online dtcerrato

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Re: Air pressure trouble
« Reply #7 on: May 06, 2021, 05:54:05 AM »
.7 SCFM @ 90 psi is way too small for just about anything in a real fancy looking unit. Our vintage electric aux. on board air compressor is 6.4 SCFM @ 90 psi. Enough to air a totally empty bus up in 10 minutes..
Dan & Sandy
PD4104-129 since 1979

Offline luvrbus

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Re: Air pressure trouble
« Reply #8 on: May 06, 2021, 06:06:04 AM »
`Takes a good size compressor to pump as much air the the 10 to 14 CFM engine compressor does ,in most cases you can disconnect the 1/4 inch control line from the governor and the compressor will pump up
Life is short drink the good wine first

Online hogi6123

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Re: Air pressure trouble
« Reply #9 on: May 06, 2021, 08:16:41 AM »
It was this one, 0.5 scfm at 90 psi.  And LOUD!

https://www.acehardware.com/departments/tools/air-compressors-and-tools/air-compressors/1000941

At 65 psi, valves between tanks open, and some small leaks start that eventually stop around 100 psi (wipers).  So the compressor got to 65 psi but couldn't make any headway past that.
1981 MC-9
1994 102DL3 (parts bus)
Central IL

Offline chessie4905

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Re: Air pressure trouble
« Reply #10 on: May 06, 2021, 08:25:01 AM »
wasnt recommending that one. Way too small for a coach. That thing is good for car and truck tires if you need a small one. Fortunately, he got by this time with the one he bought enough to move it.
GMC h8h 649#028 (4905)
Pennsylvania-central