M923a2 air issue

[sandcobra164]

I had a similar issue and threw the kitchen sink at my truck. Turned out to be a very simple but strange issue worth looking into. I replaced the drier with a Purest unit from Suprman, replaced the governor from Swampdonkey, went through the head of my air compressor (easy to do on an older NHC engine) and still had the same issue. My problem was the signal line going to the drier from the governor. It would have constant pressure once the governor signaled the drier to expel moisture at the drier fitting. I could unplug it and the air system would work fine. On my truck, it passes through a female to female coupler near the transfer case. I found the issue by working forward from the expello valve. The coupler had some kind of hardend gunk in it that was acting like a one way valve. It would allow air pressure to pass through but in doing so, would hold the expello valve open. I would let it sit overnight and it would build air pressure 1 time. After that, it would just vent out the bottom of the drier and would have no pressure in a short amount of time.

 

[cmalueg4]

Ok, will look into that also, thanks, if you had any pictures that would be amazing too.

 

[cmalueg4]

Well sandcobra164 you where correct, I could unhook the signal line n would build air, hook it up n it would leak out the dryer, so I unhooked it n blew compressor air threw the line, tapped on connections, hooked it back up, and it's works! Thanks for the help everyone! ��

 

[74M35A2]

Great volley everyone. Useful info, saved him a lot of time.

 

[sandcobra164]

Glad that you found your issue. I was almost ashamed posting my experience as I'm normally a mechanic instead of a parts changer. I guess I figured if air was moving one direction to actuate the expello valve on the dryer, surely it could go freely in the other direction. Not always the case but that's the good thing about this site, I'm not the only one who has seen some odd stuff happen on these old trucks.