M923a2 bendix unit under hood leaking air

The bendix unit under the hood is loosing air from the exh port. There is a crimped sort of cap over it. From my understanding it is part of the abs. It's not supposed to loose air is it?

Moved to correct forum

Under the hood? The air dryer under the truck? The expello port on the bottom needs to be open to vent air. If the valve is stuck and someone tried to cap it off you will have lots of issues when it gets cold enough for all the water in your air system to freeze up.

If its attached to the firewall and looks like an aluminum cylinder, that's the air pressure governor. I can't remember what it means when it steadily leaks air from the exhaust port, but replacements are very inexpensive.

Yes it is the air governor if as described by others as the horizontal aluminum canister just under the passenger windshield, not too expensive, available at NAPA in a conventional part number and waterproof part number (more expensive, same as military issue). The "crimped" plastic cap threads off to adjust the truck air pressure. If it is leaking, it likely needs to be replaced. NAPA part numbers are listed in the Excel sheet sticky at the top of this posting list.

Thanks for the info but did I post in the wrong place? Also I'm on a smartphone, does that affect me pulling up the stickies, cause I can't find them? Sorry but I've never done this before?

I have taken them apart before and cleaned them up/lubricated them and got them to work fine again.... or you could put a new one on it and be done with it also.