LRG - Well the leak is definitely from the return line (to reservoir) leaks at line at a point under the engine. I know that it is the return line because this is the only line that crosses under the engine, the "pressure" line routs in front over the radiator (insulated with black rubber) around down passenger front fender under car - not under engine. So my question is if all the fluid leaks out from return line, did it leak out BEFORE the system could equalize (or something along that line) and therefore did not allow the system to pressurize, OR does this mean that the valve is not holding pressure somehow and is merely allowing fluid through valve body only to leak out under engine? Help.