Search results

If its venting air then you have a bad inversion valve in the step box or treadle valve Only should vent with brakes applied

Bad check valve they honk. Shouldn't do that. . Leak is on the wet tank or pressure protection. Put a gauge on the wet tank drain. Fill with air. Close both valves. If it drops air pressure Down to 60psi but then holds pressure after that then you have a pressure protection side leak. If it...

Unplug the CTIS box and keep driving. Ctis may freak out and deflate all 6 tires while driving

Overspeed is for the CTIS.

Just drive it on home with that valve closed. That is what they are for.

Then you have a primary side leak. That is easier to track down if the primary loses pressure on the gauge but the secondary holds that makes it even easier since that means its not on the spring tank side

No. Its on the front of the tank itself between the fender and tank. Napa Kn23000 So the primary tank holds air once you close that valve? Compressor still cycling? If so it could be a bad governor. You can crack the drain valve on the wet tank so you can drive and the air dryer won't...

M939s are not designed like normal trucks. If the secondary is holding air it will fill the spring brake tank and take over those duties. They both send air to a valve that allows air from either tank to supply depending on which has the most pressure

Wet is under the truck. Right in front of the transfer case. Primary is top passenger tank. Secondary is bottom. Spring brake is on the drivers side behind step Primary air lines are red. Secondary are green. Pressure protection is yellow. Vent is white.

Find the leak. The air dryer only sees air from the wet tank. It doesn't see what the gauges display. You have a leak on the primary side or you have a leaking check valve causing a back flow. Shut your primary air tank valve. Located on the front of the wet tank. Your system will...