No air

[mikke60]

Started up my bus today,after sitting for 3 or 4 weeks. Couldn't get any air to build up. I hooked up an external air supply,and brought pressure to 110lbs. Disconnected the air, shut off the bus,and the air leaked out in a matter of minutes. Never had this issue before.
Second issue is a frozen brake. Usually after sitting for months,the brakes get a little sticky,but usually free up. Should prob mention temp here was just a degree or two above freezing,conditions I usually don't operate in. The bus is a 68 mci 5a
Thanks,mike s

[RJ]

Mike -

After you aired up the coach with the shop's compressor, did you do a walk-around to try and determine where the air was leaking from?

[mikke60]

I did a walk around,to no avail. I then plunged in the shop air again,and still, no luck.

[kyle4501]

Do you have an air dryer? If so, check the purge valve to see that it isn't leaking.

If that isn't it, check the air governor to see that it is still operating properly.

[Dave5Cs]

Mike what Kyle said. It is all going out your air dryer. If you filled from the rear with the shop air. If you filled from the front its in the brake system.
Dave5Cs

[mikke60]

Any chance some moisture in there froze up. This came on all at once.

[luvrbus]

Yep a 68 model MCI 5 will be a single air system it probably is frozen

[DoubleEagle]

If you do not have a heatable garage, aim a kerosene torpedo heater towards the bus at various points to thaw it out.

[buswarrior]

When did you drain the discharge muffler last?
Air drier?
When was it serviced last? Confirmed the heater element has power and continuity?

My bet is that the compressor is pumping, and the air is being blocked by stuck valving or a giant slug of ice.

Where were putting the air in from? Not the back...?

Put a heater to the air drier and see what happens in an hour

happy coaching!
buswarrior

[Ed Hackenbruch]

Do you even have an air drier?  My 68 5A didn't.

[luvrbus]

I doubt he has a drier my 1968 MCI 5 didn't have one either Ed

[Ed Hackenbruch]

If the ping tank, aka the discharge muffler hasn't been drained in a while it could be plugged solid. Helped a guy out a few years ago that could not build air.....turned out his had never been drained and was full of red rust that looked like sand when we stuck a wire up into it and cleaned it out.

[skihor]

Our 5A has only froze the brakes once, and that was @ -10* F. I do have to replace the rubber diaphragms in the rear brakes. Keeps air fine on the road but will dump the air in minutes with the air brake on.