Wabco Abs valve air leak exhaust port

If air is leaking from the exhaust port with service brake applied, the valve it bad. Air should only exhaust from the valve during an abs event or during the chuff test at key on and brake applied.

 

Are you talking about the modulator valve, the small ones on the the side of the relay valve? If it's leaking out the exhaust port only on service application, the valve is usually bad. But, sometimes they get dirt in there and chuffing them can blow it out. With full air pressure, shut the truck off, hold your foot on the service brakes and turn the key on. When the ABS goes through its modulator click test, you'll hear them chuff with the service pressure on them. If it's dirty, this can blow the dirt out. Worth a shot before you replace it.

 

Can you open them up, clean them out, and replace the O-rings? Or is it better to just replace the modulators? I had to replace my steer ones because the front fenders being loose ate a groove into the metal. In the future, I'd rather spend a few bucks and a bit of time than a couple hundred bucks if possible.

 

I personally wouldn't mess with it. If it still leaks after a chuff test with full air pressure brake applied surely the seat is damaged and not repairable. I doubt you'll find service parts anyhow, too much liability given that it's a safety device.