bus wont build air pressure

[goutoe]

I started my bus for the first time in a few months, it builds about 15 lbs of air pressure and thats all, I operated the park brake and foot brake several times, not even enough pressure to shut the engine down, I listened for leaks heard a very faint leak at the air governor coming out of a small hole in the casting? any ideas?

[richard5933]

Do you have a compressor you can connect to try and air the bus? If you do you'll be able to determine if it's a major leak somewhere or a problem with the engine's compressor/governor.

[goutoe]

Richard, I do have shop air close by, that is my next step to air it up with that, this happened once before after sitting over the winter that time I just set the park break and it aired right up, not happening this time though. Thanks!

[richard5933]

Richard, I do have shop air close by, that is my next step to air it up with that, this happened once before after sitting over the winter that time I just set the park break and it aired right up, not happening this time though. Thanks!

If you have no air, the park brake should already be set. Do you hear any air from the parking brake valve while you try to air it up?

[goutoe]

I cant hear any leaks on the parking valve, but I can hear it set and release.

[Dave5Cs]

Get some "HEAT" at a auto store or truck stop etc. Take the big line loose from the compressor head and pour the heat in that hose and put it back on. Then try to start the engine and within minutes I woill bet it will start building air. Your system is frozen or rusted and this sometimes frees' it up. empty all tanks too.

[goutoe]

Thanks Dave I will give that a try, I hear no leaks, I think something ts stuck.

[buswarrior]

A giant leak makes little noise from empty.

And that's a giant leak, only 15 lbs of air.

Broken supply hose, air drier purge valve come first. Then wonder about an obstruction. There will be very high pressure at the compressor outlet, if there is a stuck valve making an obstruction.

Pouring stuff in ahead of an air drier will turn the desicant into mud, if you think you got trouble now...

Happy coaching!
Buswarrior

[Busted Knuckle]

And another question....
Is the air compressor working correctly?
Try taking the out put line lose and see what kind of pressure it's pumping out. If it's barely putting out any pressure it could the fiber gear that drives the compressor has given it up!
Seen this more than once!
  BK 

[windtrader]

Over the winter, the bus would note air up. It would get to about 30psi and no more. There are air leaks but did not have time to diagnose the source. When the weather warmed a bit or it decided to get off strike, it fired up and built pressure back up. Probably a sticky valve that got stuck when it got cold. Still need to sort out but at least back going again while it goes where it's warm which is fine with me.

[fortyniner]

If there is an obstruction the compressor outlet pipe should get pretty hot.

But the suggestion to connect air compressor is a good start.

[goutoe]

I guess the best bet is to try the shop air if there are no apparent leaks then see what the compressor is putting out? I am still suspicious about the air governor, I could hear and feel air coming out of a small hole in the casting, is that how it is supposed to work?

[freds]

I haven't tried this but there are a number of android apps for detecting gas/air leaks.

[chessie4905]

Ears and mechanics stethoscope will find 95% of them. Leak detector liquid or dish soap diluted for the slow ones.

[Dave5Cs]

Bull on the turning it to Mud BW.
I have done it before and it works. Dallas was the one who told me about it many years ago. It will wet the Desiccant but it will also dry soon with the air going through it. You can also just change the desiccant cartridge. If you can get to the other side of your air dryer then put it in there if worried about it, but they are always in a tough area to get to.