Valve under brake pedal leaking. 03’ International 9900I

Does it leak when the brake is applied or when released?
Is it leaking out the exhaust on the bottom of the valve?

 

If it leaks out the exhaust when the pedal is not depressed it can be a back feed from a valve downstream. If it leaks out the exhaust with the pedal depressed it is usually the treadle valve that's faulty. I suspect that the new valve is faulty or a piece of debris found its way inside the valve when you were replacing it.

 

Take off all your delivery lines one by one to see if any of them have air back feeding. Air back feeding from another valve will leak right out of the exhaust of this one, leading to replacing this valve for nothing.

 

Another valve that could be back feeding up a signal line is a rear relay valve. This will be leaking back up a green line if that was the case.

 

Maybe take the drain valves out of the air tanks and see if one is full off rust. I replaced a couple of leveling valves and foot valves in one because of that.

 

I just stuck a pencil magnet up in them and a ball of rust came back.