1937 terraplane

2manyprojects

what is the correct pressure radiator cap ? thanks

54coupe

They are an open system. The vent tube is not connected to the neck where the cap can regulate the pressure within the cooling system. I don't think the original caps even had a spring under them... This is true of my 36. I believe 37 is the same.

Jon B

Mine's never had a pressure cap, yet remains cool.  Idled for 15+ minutes in mid-90's heat, while waiting to park at a local car show a couple years ago. 

BigSky

My 37 has a cap with no spring inside, just the cap.  No overheating issues here either.