923a2 air brakes leak

[RustyM923]

This a little off thread, but I'm having problems with my 923a2 intermittently rapidly leaking down its primary air supply. The secondary stays good as long as I don't draw much air. As soon as I rev the truck up, that air comes back up to 120 +- psi and sometimes stays there fine; other times it drops back down to about 20 psi if I let the truck idle. I've walked around the truck and I hear no leakage, and when I parked it a little while ago the air stayed up, even at idle. Any ideas?

Thanks for letting me hi-jack the thread.
Tommy

Break out a spray bottle of soap and water and start spraying everything. It's got to be leaking from somewhere.

 

[Tommy Frantz]

That's my next step. I had just parked it about 1/2 hr. before my post and haven't had time to soap everything.

 

[jwesley74]

This a little off thread, but I'm having problems with my 923a2 intermittently rapidly leaking down its primary air supply. The secondary stays good as long as I don't draw much air. As soon as I rev the truck up, that air comes back up to 120 +- psi and sometimes stays there fine; other times it drops back down to about 20 psi if I let the truck idle. I've walked around the truck and I hear no leakage, and when I parked it a little while ago the air stayed up, even at idle. Any ideas?

Thanks for letting me hi-jack the thread.
Tommy

Check the air dryer. Ours was leaking out bottom purge vent. Had to do rebuild on it. But same problems you listed. Wouldn't build air or it would drop air rapidly.

 

[mikey]

Check the air dryer. Ours was leaking out bottom purge vent. Had to do rebuild on it. But same problems you listed. Wouldn't build air or it would drop air rapidly.

Agreed. Check the air dryer! Same exact symptoms with my 939. Mine seemed to run great when it was warm outside, which led me to believe there was an issue with ice. However, you state that you hear nothing. I could clearly hear air being expelled from my air dryer purge valve when the truck was running.

If your issue is the air dryer, make sure you get both the upper and lower rebuild kits. The upper kit has the purge valve, which was absolutely the problem with mine and seems to be common and the lower kit has two filters, which you will need to change if you don't want the purge valve to stick again.

http://www.amazon.com/Haldex-Midlan...396554087&sr=1-1-fkmr0&keywords=haldex+dq6020
http://www.amazon.com/gp/product/B0046PEL2I/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

Mikey