-
Hummmmm:
So it could leak back through the main line and out the compressor with out affecting the brake tanks. Will have to go down that road and see where it goes.
Jon:
Have done the drain down test per your suggestion, safety valves work. On a side note; before I replaced my brake relay valves and had a slow leak down on the brake tanks the Aux tank would drain down to zero with the brake tanks. Since replacing the brake relay valves I have basically no brake tank leaks, just a slow leak in the Aux tank.
As noted, brake tanks stay at 120 PSI for months before slowly leaking down further (maybe 1/2 PSI a day if that). Aux tank will drop to around 70 PSI overnight, then take another 4-5 days to reach zero while the brake tanks remain at 120 PSI.
The leak is in the Aux and is small enough that it’s not a priority to fix but more a challenge
Chuck