any suggestions (brake valve air leak)

Get it replace, this is a serious issue that needs to be replaced.

 

You bneed to get someone to help you and find where the air is leaking to start with.
Why are you pushing the brake pedal when the tractor valve is out to start with?

 

Again, why are you applying the brake pedal with the tractor valve out (truck brakes are set)?

 

Probably, I do not think it should leak while you are applying pressure, but don't really know. You should not be applying brake pressure from the pedal while the brakes are set though, it can't do anything anyway, and for all I know the air may have to go somewhere, I don't remember ever trying it.

 

Sounds like Trailers got a leak somewhere, feeding back through parking valve. That’s normal when Trailers leaking. Chock tires and shut Truck off, Brakes released, listen/ look for leak on trailer,then apply trailer hand brake, check again. Park brake valve, leaking, and stopping when wiggled, usually means it’s going bad, that’s a separate issue, replace it ASAP, it will soon leak non stop. Possibly shutting you down.

 

did you hook blue to red and red to blue. it will make air feed backwards threw trailer brakes back to the dash valves