ABS Combo Brake Valve Leaking Air

Does it do it with the park brake set as well?

 

Check make sure none of the chambers are leaking internaly by punching the service side hose and see if the leak stops if it's not chamber then it it relay valve itself it is possible to buy separate and not whole assy about 100 usually unless he has fancy abs system

 

If it leaks out of the bottom exhaust all the time, the valve is no good. If it leaks out of the bottom exhaust only when the parking brake is released, then one of the brake chambers is bad.

 

One possible source of leak is a failure to keep sludge out of the system, it gets into the chamber seal between the spring side and the dry side erodes the seal and boom leak. You will literally watch your air drain out of there and wonder if your springs are going to apply and finish your stopping.

 

Like nasriza said. Pinch off the lines at the service port of each brake chamber, one at a time with the brakes released. When it stops leaking out of the valve, you've found the leaking brake chamber. Just chock the wheels first!

 

Pinch of the emergency side line at the chambers one at a time if leak quits when one is pinched it's bad