[encantotom]

something to keep in mind is that with the checkvalves that are there, the brake system always wins in getting air pressure. if the supply system is not leaking, but the brake system is, the brake system will drain air from the supply side. that is why if you park, and the brake pressure is higher than the supply pressure, as the brake pressure bleeds off due to a leak, that when it hits the supply pressure, the two then will go down together.

realistically, the brake pressure should hold for a long time. a common problem is that those checkvalves stick and since the supply side will always leak down, then if the checkvalves are sticking, then the brake pressure will go down at the same time and not hold.

alot of us have ultrasonic leak detectors to chase air leaks. and ALL of us chase air leaks.

tom