M939 series truck - Air tank air lost - Bad treadle valve - diagnostics

Diagnostics on determining if you have a bad treadle valve or a bad brake relay valve/diaphragm. Whatever tank is leaking down you need to block off the port going to the treadle valve and vise versa to determine which was the leak is happening to the rear of the truck or to the front of the truck.

You will need to hook an external gauge to your tank drain to monitor air pressure lost OR you can simply air it up and let it sit till you know your tanks would have been empty before and then drain the tank in question and see if it is or isn't holding much air pressure.

Treadle Valve replacement part is Bendix # 286775

Видео M939 series truck - Air tank air lost - Bad treadle valve - diagnostics канала Wes Simpson