Truck losing air pressure while stopped can’t find leak

[Rawze]

(04-27-2021 )Redland1 Wrote:  

(04-27-2021 )Rawze Wrote:  Some leaks will stop when the air system gets below 90-psi... Put air up all the way to 120 psi and shut engine off, then key-switch back to on position, jump out before it drops back down.

The only way it goes up to 120 is if I drive it above 55MPH.

then it will not pass a 112-point D.O.T. inspection!. .. you need to get that air system fixed right away, as the truck is dangerous!.

If it will not get to 120-psi at idle, then the air dryer/govenor is shot!... that or the compressor!