Air brake problem

[frank-id]

The solution is to melt and ice and then remove water. Pour common rubbing alcohol into the large hose leaving the air compressor. Open bottom drain on air tank the greatest distance from the air pump. Reconnect line from air pump and start engine to make air. The alcohol may go completely thru the air system and melt ice and absorb water. Here is chilly Idaho, I have used 5 pints of rubbing alcohol on a 2 axle GMC bus. When leaving a bus in cold weather, open all the drain vales until the time of use. Frank

[lapeer20m]

is it below freezing now?

i'm from michigan, and have learned first hand that when it's cold ice can form inside the air brake system. however, once it's above 32 degrees all your problems should go away. Dissconnecting the main air line from the compressor and filling the line with isopropyl alcohol then re-attaching the line is a great way to remove ice from a line.

if it's been above freezing long enough for everything to thaw then i suspect your problem is unrelated to not draining your tanks. Tanks aren't drained to keep them from freezing, they are drained to remove the buildup of water and ickyness from the system. If a tank is half full and freezes it won't hurt anything. It's unlikely that your tank was full (or even half full for that matter) of water in which case it could burst when froze.

are there any air leaks? does the pressure gauge move at all? Is the compressor turning?

here's something you could try if it's warm enough outside that you've ruled out ice still being in the system. If you have access to a 110 volt air compressor and can bring it to the bus: use a wrench to remove the drain valve from one of your tanks. The fittings will be NPT, most likely 1/4". install in it's place a fitting that allows you to connect your 110v air compressor to the tank. Let it build up pressure.....maybe up to about 80 psi. now shut off the 110v compressor, then go start the bus and see if the air pressure increases. You can throttle the bus up a bit with your foot...if your compressor works it'll build pressure faster when the engine is turning more rpm's. You can step on the brakes a few times which should make your pressure gauge fall...then see if the bus builds any pressure on it's own.

if after all that your bus doesn't increase the air pressure, then i would assume there is a problem with the compressor...perhaps in the regulator.

[the_experience03]

Originally Posted by lapeer20m

is it below freezing now?


if after all that your bus doesn't increase the air pressure, then i would assume there is a problem with the compressor...perhaps in the regulator.

That's my issue. The regulator that was iffy last summer is dead for the most part now. After high idling for 30 minutes I did eventually see air the last time I ran it, but the regulator is getting replaced before the bus leaves the driveway.

[lapeer20m]

Originally Posted by the_experience03

That's my issue. The regulator that was iffy last summer is dead for the most part now. After high idling for 30 minutes I did eventually see air the last time I ran it, but the regulator is getting replaced before the bus leaves the driveway.

do a photo documentary on that and post it here, will ya? I've never disassembled the regulator. I don't really understand how it works...what makes the compressor stop compressing even though it's still spinning?

[the_experience03]

As I stated, I have exactly the same problem right now though mine will eventually make air. I do plan to document my governor swap when it warms up, but if you wanted to do it first that would be great. Then I could just add to your thread so we could have two examples (assuming that is the problem).

[the_experience03]

I watched the gauge as it fluttered and didn't always cut in and out consistently. I figured it was the regulator so I listened to it close and smacked it with a hammer. Since that resulted in a change in the performance of my brakes I could deduce that was the source of the problem.