Help tracking down air leak

I couldnt find my QR valve.....but there isnt a dam fitting on the rear of the chassis thats leaking. I soaked the #### out of every connector/fitting and line back of the cab..

 

how hard is it to remove/repair/replace this thing?

The more I think about it...The fact that air leaks MOST of the time but not ALL of the time sorta eliminates any hoses/fittings - I would bet if its a hose/fitting it would leak and leak all the time....like water does.

2 out of 5 times I release my tractor brakes I hear air escaping. The other 3 times I do not. In fact, sometimes when I hear air, I pop the valve back out and back in again and it quiets down. It's not the valve but doing that seems to do something...


I suspect my problem will end up being a VALVE and/or one of those sending units on the twin manifolds that monitor psi. Those could leak intermittantly and cause my issue....maybe...

 

Here is the actual culprit of the air leak. Its a pressure valve. So I was on the right track at least...Its in the parking brake air circuit and was rather buried. I found it by tracing out wires of all things....It was tossing air out the back and side like you wouldnt believe. $21 at KW.

 

Well...air is leaking when the truck sits. But thats not as critical as something like this. Thats my next issue to track down. After about 3 days my primary tank is down to around 30psi and the secondary tank is still near 90.

So since I am not sure where to start to tackle that, I havent.

I thought it might be my airbag suspension so I 'dumped' it one weekend and it didn't change the air loss. I found the sleeper air bags leaking and replaced those. They dont leak now, but that didnt help either. Found my interlock switch leaked. Replaced that and it too didnt help.

You cannot hear any air escaping at all. At least I know whatever the issue is, it's not inside the cab. Hell I have soaked things so much with soapy sudz its not even funny....