Reply to "Radiator cap for the stainless swirl tank"

Hi Steve, a 15 Psi Cap starts to release pressure at 15 Psi. If it does not seal up to that pressure it is either faulty or is a mis-match for the filler Neck (common problem). If i.e. you use a Cap which is really designed for a 19mm deep Neck on a filler Neck that is 26mm deep. It will not hold the pressure ;-( You could use double layer of Rubber Seal etc. but the right thing would be to get a Cap that is designed for the depth of your filler Neck. (assumed that was your problem) The release pressure is a function of Spring load and Area of your Cap Seal. Problem arise if the Spring does not get the proper load because it does not reach the bottom of the filler neck. Anyway an indication is that you must have to press hard down on Cap before you can twist it. If Cap feels loose and can be twisted/turned without too much effort I would suspect what I mention above.