I've been reading the forum about radiator caps, but remain confused about the different pressures available. The radiator on my 41 AK with a 54-235 has a vent tube coming out of the top of the radiator. I don't see how it is possible to have any pressure in the system, regardless of the cap rating. What am I not understanding?
You heat water in a closed space (cook pot, radiator, etc.) it builds up vapor and expands. The vent tube is an overflow. It's common for radiators to overflow if/when they are overfilled. Your 41 radiator is (probably) rated at 0 psi. You can add a coolant recovery system rather easily...
Modern radiator caps have two seals, the blow off tube is located above the lower seal and inside the space between the two seals, allowing the expanding coolant to flow out to a tank. When things cool down, a check valve opens and allows the coolant to get sucked back into the system.
~Charley 1954 Chevy 3100 with 235 “Bud” Follow along in the DITY 1963 Chevy half ton stepside short box 230 1954 GMC 3 ton 302 And several more Chevy camper and work trucks 1979 1987 1996
If you have an original '41 radiator, you do not want to use anything above a "zero" cap. The design of this style of radiator cannot handle the pressure. I seriously doubt that a two-seal "zero" cap exists. Maybe you could alter a 4# cap to vent at one pound, but I don't know if a 4# cap will even fit on a '41 radiator. Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
Since my radiator is vented on top, above the cap, I see now that none of the caps would create pressure in the system. I just need to run the fluid level a little lower so not to dribble anti-freeze from the vent tube.
Acceptable level is about 1/2 inch above the fins/tubes. ðŸ›
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
tfisher I guess I misunderstood your description of the radiator vent. Sorry. I have only seen radiator vents coming off of the neck, above the seating surface of the cap.
Just goes to show your never too old to learn something new, if you're willing... On the HAMB swap meet there's a custom 52 Chevy Panel for sale that has a SBC. I think it has a GMC radiator and it has a vent tube in the top of the tank. See picture. Is yours similar to that?
