Radiator Cap

[robertw144]

Greetings folks.

I have a 1955 Cub. The radiator seems to be leaking when it gets hot. However, I think all it needs is a new radiator cap. Can someone tell me if this is a special cap or will any old NAPA cap work?

Robert Gross
Groveland, FL

[staninlowerAL]

Someone else can verify but to the best of my knowledge the cub radiator is designed to run at atmospheric pressure, no pressure cap. This might have changed in the later models, I don't know. Stan

[Scrivet]

Most Cubs are not pressurized (nor do they have a water pump). The most likely cause of leaking is being overfilled close to or right up to the neck of the radiator. If you look in the radiator with a flashlight pointed at an angle past the baffle you'll see the tops of the tubes. Anything over the tops of them is fine. The top of the radiator is the expansion area for when the coolant gets hot and expands. If it's full already the only place it can expand is out, thus the most common leak.

[cballman]

I have a Cub tractor with a replacement radiator. It needs a cap also. I have found the NAPA cap is not deep enough to keep coolant in the radiator. I am in the process of finding a cap that has a long reach or deep reaching cap. You need to measure the depth of the top of the radiator and then depending on the size you will know if a NAPA one would work.

Charlie

[shawman]

I have been wondering about the radiator cap myself. My cub came with a 7 lb. cap on it, my cub is a 1953, should it have a no pressure cap?

[Scrivet]

A Cub is supposed to be a nonpressurized system (except for the long stripe production years '75 or so on through '79). Here's what it should look like courtesey of TM until they retire in a couple months. http://www.tmtractor.com/new/co/1642fp.htm