Air constantly building up/leaking

Does the air leak down that fast with the engine not running? Some parts like fan hubs and turbo actuators are air controlled and only work when the engine is running, so shutting off the engine to listen for leaks won't work in that case. If it does leak with the key off, your leak is so bad it is silent, you just have to keep looking for it.

 

More info would be needed, but it generally doesn’t work out to go fixing things without knowing they are broken. The leakage isn’t excessive (Using CVSA standards) but I know it’s probably irritating. It can be anything from a small spring brake leak, fan hub leak, turbo actuator, transmission controller leak, any air switch leaking or any number of other things. If one tank is leaking down it could be the one way check valve, if both P & S are leaking down if could be a two way check valve leaking. Internal system leaks can be a biotch to find but they can be found. Just be patient and methodical and avoid fixing things you are not reasonably certain are bad. Just noticed you stated it doesn’t leak with the eng off. How about with the park brake released with the eng off?

 

Your cut in pressure is too high. You may have leaks in the system, but. I suspect you have an issues with the unloader signal to the compressor. If you have a leak in the unload line from the governor to the compressor this can cause a similar complaint.

Get it in the shop and charge the system with shop air until the dryer purges and check the entire system for leaks. With the truck not running audible air leaks will be much easier to pinpoint.

Dont forget to chock the wheels and check for emergency and service brake air leaks.

 

Bendix makes the D-2 governor with cut-in pressures every 5 psi from 90-115. The D-2 P/N 277486N has a pre set cut-in pressure of 110 psi and is common. As long as there is 30 psi or less difference between cut-in and cut-out pressures it’s fine. Better to be closer than too far apart.

 

I could buy that. Not all that common for me to see.
Everything I see is ADIS with the fixed governor. 110 is high. And 105- 130 is typical. Regardless the 2 minute cycle time is waaaaay short.

 

Yep it is. I would endeavor to find the problem. It’s not terribly bad, but one thing I know about leaks. They do not get better with time, they get worse.