R-12 Valve 065303

I just replaced one on my old White. It was leaking from exhaust with or without park set. After replacement it still leaked out exhaust with park set. Turned out that problem was one bad 30/30 bleeding back through its service hose. Made no sense to me but new 30/30 fixed it.

 

Just to add. The 30/30 that was bad made no sounds or symptoms of leaking until I disconnected the service lines from the new valve thinking like you that the new valve was bad out of the box. The LR 30/30 was the only one that still had air flowing out of it’s hose. The other 3 did not.

 

The 9400I I was talking about had black chunks of stuff in the valves.
SmallPackage is probably more on line with air backfed from somewhere else.

 

Is that rust powder/grit circled in red? Can you wipe that off with your finger? Or is the valve aluminum and corroded? If so that is probably getting between the seal and housing and causing leaks.

 

This is most likely a booster, quick release valve or modulator valve thats bypassing meaning it doesnt close when it should and air is escaping through the foot valve. Happens frequently on all trucks.

 

You can just pinch bith service brake and parking brake hoses 1 booster and a time. Valves too. When the leak stops you found your culprit.