tractor release valve?

You say you hear air leaking, where is the air leaking at? If its leaking down at a brake chamber, one of your spring brake chambers has gone bad. The dash valves, for me at least, don't usually fail with a big leak, they start leaking very slowly and then you eventually have to replace it. Or you could've had one of the lines going to the valve fail. The key is finding where the leak is.

 

I've had to replace the dash valves in both of my trucks, so if your hearing it comeing FROM them then yea thats the valves.

Our shop guy did tell me though that tractors have a valve somewhere else that sticks and makes the valve inside leak. I can't remember where or what the other valve does.



American Trucker

 

Once you push in the tractor knob try pushing down on the brake pedal one or two good times, that may get it to stop.

 

Those park brake valves are all plastic. When you push the button in and you hear the leak try to wiggle the button up/down or side to side. Sometimes it is just the oring not properly seated and needs an adjustment.

 

If this happens only when you Bobtailing, shut off the truck, leave it in gear so it won't roll. Make sure your all aired up, push in the tractor brake release & get out side & do a walk around. Double check everything by your Front & Back Brakes.
If your hooked to a trailer, Do the same things but with your trailer brakes released also. Alot of times you will hear the leak at the valves but the leak is elsewhere, including where your glad hands hook up.
And I'm having a hard time believing you've got 21 years driving trucks.