Giting it up -- bus air that is

bebackbus · December 18, 2010, 03:27:50 PM

Just an update on the air tank. I ordered a new one from Yuma Diesel and they cut off the mounting tabs for me. I also used a T instead of the two inlets. All a ok except the air won't build from the engine. Zero pressure. Outside household air compressor 12o psi.

Long story short. With Ed's help found that there is a small tank right off the air compressor. It is about 8 inches long and could be drained in theory. The check vaalve and the fittings on the tank were totaly clogged with gunk. Now it airs up very nicely. Now the valve to drain it works too. Who knew?

RJ · December 18, 2010, 05:13:48 PM

That little tank right off the air compressor is called a "discharge muffler", or, more commonly, a "ping tank."

Not a bad idea to open the valve and blow out the gunk now and then, more frequently in humid climates.

Off the top of my head I don't remember where it is on the other brands, but on GMC highway models it's on the overhead just inside the transmission access door.

FWIW & HTH. . .

brando4905 · December 19, 2010, 05:45:52 AM

RJ,

Good to know what that is now!

So, do you just unscrew the plug on the bottom and let the compressor pump to clean it out?

Thanks,
Brandon

Ed Hackenbruch · December 19, 2010, 06:17:33 AM

Brandon, they usually have a valve with a short length of tubing on them from what i have seen. On my 5a the ping tank is mounted on the bulkhead wall.

5B Steve · December 19, 2010, 06:57:08 AM

Would it be possible for someone to post a picture of that ping tank? I have that problem sometime when mine will not air up!

Steve 5B.........

Oonrahnjay · December 19, 2010, 07:35:07 AM

Beb - what did you do to clean the tank? I don't have one of those "ping tanks" on my bus but if I had any kind of "gunk" buildup sufficient to stop the compressor airing the bus up, I'd do a thorough cleaning of that tank and those valves that are attached to it. I'd also check the compressor (too much oil blowby?) and any lines between the compressor and the dirty tank. I'd also check the lines "downstream" of the tank, too.

Air systems should have a good air filter on them (mine draws air from the main air filter, before air gets to the intake manifold ... others may be different) and a frequent check for dirt and oil. Keep a good check on your tank drains, too. I wrap a piece of paper towel around mine before I pull the cable so that I can see what's being blown out.

Air systems need to be clean and dry. If they're not, you get contaminants in the valves in the "master cylinder" (don't know what the valve system under the foot pedal is called on buses but you know what I mean), the fittings in the systems like one-way and pressure regulating valves, and the valves in the wheel cylinders. Worth a look at any time you find anything of concern and on a regular basis for maintenance.

bebackbus · December 21, 2010, 09:35:22 AM

I took the tank off and had a shop pull the fittings. I could then stick a screw driver into each fitting and ream it out. I also did the same with the ping tank. I then ran 2 cans of pb blaster thru them. On my rig there is a valve to drain but it never worked. Now I know why. I talked to a couple of bus guys and there are two reasons that make sense as to the tank plugging. First on a 4106 the clean air comes from the air cleaners that are oil bath. If the cleaners are over full with oil the air intake will send oil into the compressor intake. Second reason is from excessive idiling it will also load up. I don't idle it but the problem was there from the PO. The tank was so full of gunk that at fast idle the air would not build at all. 0 on the guage. Interesting though was that with the tank plugged some air went to the shut down valve. I could shut the bus down with 0 air pressure. Also there is a check valve inline that I replaced. Didn't think it could be cleaned.