Thanks Chryco
So I guess my 1 week old cap is bad already? At operating temp, with a vented cap, system should have pressure, correct?
Taken from the stant link above....
" VENTED Radiator CAPS
There is one coolant cap that is quite different others: Stant #10231. Some people think this cap is broken when they first see it because the part that goes into the fill pipe to seal the system “wobbles.” This is a vented coolant cap. A “Vented Coolant Cap,” sometimes referred to as a “Partial Pressure” cap, may not immediately let the system realize pressure upon thermal expansion (warmup).
The cap has a small disc at the bottom of the cap that is a vacuum valve. That vacuum valve hangs down in the open position until the cap is subjected to rapid expansion of coolant or steam, which closes the valve in a sealed position. At that point, the system is pressurized and helps control overheating and enhances system efficiency. This also means the vehicle can be idling without having a pressurized cooling system and could be “venting” vapor into the overflow reservoir."
So what does this mean....
"This also means the vehicle can be idling without having a pressurized cooling system and could be “venting” vapor into the overflow reservoir."
