I'm very close to starting my car for the first time in nine months after having to replaced the head gaskets due to water leaks out the back of the heads. Since the water was out of the system I changed the heater hoses and a number of other things. I decided to pressure test the system before filling it to save me the grief of coolant on the floor or worse in the car. I did this by building a gauge manifold with schrader valve that I screwed into the 3/8" water temp port in the block. I fired up my airbrush compressor and pressurized the system. What I found is that my radiator cap blows off around 10psi. I put another rubber gasket under the cap (I found this idea in a prior thread, thanks Doug) but that only got me to 11.5psi. So My question is what cap are you using with the stainless tanks the vendors sell? I'm assuming all the vendors sell the same tanks from the same source, at least they all look identical that I have seen. I tried another cap and that one was worse. The better of the two came with the tanks from the vendor when I bought them a couple of years ago, it's not the original euro cap. What cap are you using and have you tested it?
Steve
Original Post