Well, I had a leak in my air tank. Every time the truck would sit for a few hours, I would have to top off the tank. I found that the brass fitting that adapts the 3/8" male NPT fitting on the solenoid to the 1/2" female NPT fitting on the tank had cracked and was letting out a ton of air. I went to my friendly neighborhood Harbor Freight and picked up a $1.99 fitting, and all is right with the world now. How much pressure is exerted on that solenoid when it snaps shut on 200 PSI? Obviously, it was enough to crack brass…cheap Chinese brass!