M923 Not Building Air Pressure

[0352]

The truck is a 1985 AM General M923A2. I just started it today but, it would not build air pressure. The air seems to be leaking out of an air purge attached to what I think is the air dryer (Pictures Attached). I can't find any air leaking from any other place on the truck. Any help would be greatly appreciated.


UPDATE:

I took apart and cleaned the lower assembly. The truck now seems to work properly. I will still replace/rebuild the unit for proper function, but now I can at least move the truck. Thanks to everyone for the quick response and links.

 

[porkysplace]

Have you serviced the air dryer ? New filters and such ?
[h=1]M932a2. Air dryer blowing air[/h]
[h=1]M923a2 Air Dryer rebuild[/h]

 

[juanprado]

very common.

You can take a screwdriver or 3/8 socket extension in the middle of the hole and push the piston back maybe 1/2 inch. Squirt plunger area with silicone spray lube to help you keep it lubed.

dryer needs to be rebuilt. Complete top to bottom kit is 100-120. Several epay and ss members are selling new complete dryers for $140-$170ish.

I rebuilt mine since I had secured the parts before lots of them came out on GL. In retrospect, I would have bought new and been done with it.