Problem with the leveling system or air leak, need help please

[bcbusman]

Just got an 1979 MCI MC-9. When I got it home I could hear air leak and believe is the air beam leaking on the passenger side. The bus is leaning to the right meaning the driver side is inflated and the passenger side is completely deflated and won't inflate anymore. It could be air hose. I can hear it between the rear diff and the air dry tank. I guess the only way to see it if from under the bus or taking off the wheel should give me enough clearance to see whats going on ? Also what is weird now is when I start the bus, the air pressure just keep raising , no purging, can't release the brakes, can't turn it off ( no air ) After I turn off the bus and let it sit for couple minutes the air just starts going to the air tank that supplies air to the park brake and engine shut off valve. Going crazy here. Any help would be appreciated.

So now the air pressure sits at 150, had to run in the back and shut it off manually. Things that don't work are wipers, fast idle, park brake release, fan belt tensioner, air horn, all the right side airbags are down, NO AIR, which air tank operates all these ? Can the leveling valve be stuck open ? Is there two leveling valves in the rear that control the front also ? The tank doesn't purge at 120 anymore.

[chessie4905]

   Apparantly this bus has been sitting for a while? The air compressor governor is hanging up. Try removing it and clean. Or just buy a new or rebuilt,as they aren't expensive. Then you/we can work from there on some of the other issues. Since this is going to be a long term ownership?,you should obtain a factory service manual of some version.

[RobSedona]

wow thats a lot of things at once do the air compressor governor  as chessie said then one thing at a time

[bcbusman]

The air compressor is pumping no problem, but the air is not dumping at 120 anymore. I drove it home ( 3 hour ride ) and no problem, it was dumping little passed 120 all the way. I parked it and was hearing this huge air leak in the back. I have to shut it off manually and couple times like 2 minutes after turning off the engine I would hear the air would just start going from one tank to another and then I can hear the air leak. Now nothing, it just pumps air without dumping.

[lostagain]

Replace the governor first.

JC

[bcbusman]

Where is the governor located ? Is it possible to get the part number ? Can I take it apart and clean it ?

[Timkar]

Governor is on the compressor. Yes, you can take it apart and clean it, but getting new seals will probably cost more than this...
http://www.ebay.com/itm/Bendix-D-2-Air-Governor-/171811693006?hash=item2800c661ce&vxp=mtr

[bcbusman]

I did order it, thank you for the link, what is the exact function of the governor ? I know it governs air  but to one air tank or 2 separate ones ?

[lostagain]

The governor is usually located on the compressor, or close to it. It is the device that senses air pressure and tells the compressor to cut in at +-90psi, and cut out at +-120psi. Yours might not be telling your compressor to quit pumping, that is why you are getting 150psi. There is a good chance that most of your problem is caused by a faulty air pressure governor.

JC

[bcbusman]

Thank JC, will start with the governor, where it should be on a 8V71 ?

[lostagain]

It is usually mounted on the compressor. If not, look for it using the picture in the link Timkar posted. Sounds like you need to get yourself a maintenance manual for your bus.

JC

[bcbusman]

compressor is rear mounted so its easy to access I suppose ?

[eagle19952]

compressor is mounted so its easy to access I suppose ?

not usually. at least not on a coach.

[bcbusman]

I can officially say that selling my Setra was the biggest mistake. That bus is the best engineered bus with easy access to everything.

[eagle19952]

I can officially say that selling my Setra was the biggest mistake. That bus is the best engineered bus with easy access to everything.

i have not read every word posted... but it is it possible that the governor is simply mis-adjusted ? by someone who was trying to solve a problem incorrectly ?