Radiator Cap

Posted by KD On 2014/5/6 14:54:08

Anyone have experience with what radiator cap works best on a V-8 car? I have a 1955 Clipper Super with a 320 CID V-8 and it came to me with a 7 lb. cap. I had a leak that appeared, but could not find the source. I added more antifreeze, (probably too much) and lost the additional out of the overflow. It seemed to "level off" (no more lost antifreeze) and didn't seem to leak. All seemed well. For good measure, I pressure tested the system to 12 lbs. for 45 minutes - no issues. I replaced the 7 lb. cap because I thought it to be faulty (plus it was old). Packard specified a 12 lb. cap. I used a 13 lb. Stant because I could not find a 12. Several good sources told me this was not an issue. Days later I had a leak under pressure from the upper end of the core while driving. Strange this leak never appeared before - during the engine run or the pressure test.

So.... now I will have the radiator re-cored, which is a maintenance item I wanted to perform anyway. Before I put it all back together, I'd appreciate some opinions on the proper cap.

Thanks!