923a2 air dryer makes noise after shutdown

[smokem joe]

New to me truck. I'm going through it changing fluids and greasing it. Moved to forward and shut it down to grease u joints. Air dryer was making a noise I can only describe as like a duck quacking. I have driven semis for years and never heard anything like this. Any ideas what would cause this? I am working my way through all the TMs over the last couple weeks but haven't seen anything for this.

 

[simp5782]

Is it leaking air from the bottom of it? or just an internal sound? Could be a bad O ring on the canister seal letting air get by. I have heard that noise but it sounds like a squeak over a quack.

 

[smokem joe]

I couldn't feel any air leaking anywhere. I have air leaks all over I'm chasing but nothing there. It was supposed to have been a new unit within the last couple years.

 

[smokem joe]

Got a wiper question too. I hear air coming from passenger side wiper motor when truck is shut off too. I replaced windshields today and there is air coming from supply line for a couple minutes after shutoff. Bad wiper control? Sometimes wiper randomly starts on that side when the truck is started too.

 

[simp5782]

Got a wiper question too. I hear air coming from passenger side wiper motor when truck is shut off too. I replaced windshields today and there is air coming from supply line for a couple minutes after shutoff. Bad wiper control? Sometimes wiper randomly starts on that side when the truck is started too.

Bad switch it is letting air by. It goes away after shut down cause it is bleeding the wet tank down thru the pressure protection side. Once the wet tank gets below 60psi the air to the wipers is cut off automatically. The main and secondary tanks have one way check valves so the air from them can not feed back to the wet tank when its pressure drops.

Feeling for air isn't going to get you anywhere. You need a soap and spray bottle i am sure you know. You can find any leaks with that.

 

[smokem joe]

I was thinking the control was bad. I'll have to look up the nsn and try to find one. Any commercial equivalent?

I'm using leak detector that I use on gas and air lines in commercial buildings. As you know there are a ton of lines and fittings on these so it is taking awhile to go through it all!

 

[simp5782]

RM1720221 is a midland number but its pricey and a different variant. Just buy one from surplus. Alot cheaper