Radiator Cap

Having trouble locating a STANT R8 4 lb radiator cap OR ANY OTHER BRAND for my 48 Windsor 6cyl.

Tryed NAPA,BARRY'S, ADVANCE,AUTOZONE, OLEARY,PEPBOYS,E-BAY, GOOGLE, HELP!!!!

I have a 4 pound cap, that will fit. But aren't you running the original non- pressure rad with the original C38 251 W or S engine. If so the rad is a non-pressure design and does not require a presurized cap. But if you have another rad in your car from say a 1951 or later it will need a 4 pound cap, as these were the first pressurized systems Mopar built. I do have a brand new 4 pound cap if you need this and cannot locate one in your area I could sell you this one, $7.00 US plus postage and pop it in the mail and you would have it in a week...............Fred

I never paid much attention to the cap but now that you mention it the radiator neck does not have an over flow tube. There is soldered item about 4 inchs from the neck with a metal tube running across the top & down the side. Stant R8 cap I have appears to fit kind of loose. This car only has 30,000 miles on it and was purchased from the original owner so I have to believe the radiator is the original as I just replaced the original crumbling hoses. Where would I look for one of the non-pressure caps?

Vintage Auto parts, Roberts Motorparts or the PWHM 1946 to 1848 Chrysler website. I was looking on the Vintage Auto parts website this morning and they advertise non-pressure rad caps for $8.95 plus shipping. As for your car and rad coming with a 4lb cap as OEM, not likely, There is no overflow at the rad neck because it's non-pressurized and does not require a pressure cap,although it would still work. The overflow is on the top of the rad, when these cars overheated and boiled, it would simply go out of the top overflow tube and spill out. On a pressurized rad from about 1951 and later with Mopars, the 4lb cap would be lifted off it's seat when these rads got too hot and there overflow tube was in the neck of the rad as is the same on modern type rads. the non pressure rads cool by pure convection, water will boil at 212, when you pressurize a cooling system you raise the boiling point of water by 3 degrees for every pound you increase pressure. Years ago they use to change to alcohol based antifreeze in the winter, then change back to water in the spring as the alcohol would boil over in warm temps.I would simply run your cooling system using modern antifreeze (Prestone), with a 50/50 ratio, install a 160 thermostat, this should allow your cooling system to run at 160 to 165, which is about normal for these cars and engines. Hope this clears things up for you...............Fred