VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1938 Chevrolet Master new radiator

I have finally been able to drive my 38 Master with my newly re-bored 216, new radiator and heavy duty fan. the radiator was purchased from the Filling Station and was made by the Brass Works. The radiator was pretty close to the original but didn't quite fit into my Master. I had to trim metal from the lower panel in the nose that acts as an air dam for the radiator flow. The lower lip of the radiator where the lower tank joins the core would not fit in back of the panel.

So I took my first test run the other day. When ordering the rad, they asked me whether I would like the pressure neck option and I said yes. I put on my non pressure cap thinking that it was an option that could choose. After about twenty minutes of driving I pulled into a gas station and noticed that my right front fender was covered in coolant. Unfortunately my flashlight was broken so I filled the rad up as best I could and drove home. Upon examination I discovered that the top tank is not as tall as the old tank. Also the inlet for the top hose is very close to the top of the tank. the pressure neck has the overflow near the top of the neck which is very close to the same level as the top of the inlet from the engine. So with my non pressurized cap, at higher speeds and flows the coolant was simply pumped right out of the overflow pipe in the neck. I replaced the cap with a 4 lb pressure cap and everything works perfectly but now I do not have the choice of using a non pressure cap.

If you plug the overflow you will blow out the radiator. As the coolant heats up it expands and needs more space so a release is necessary.
Having to run a 4 pound cap is better than what the original 1938 would be as they were a hot running engine, (that includes 1937 to 1940)....that is why Chevrolet marketed an overflowtank in 1938.

Thank you for that correction Gene. Post has been deleted.

Of course I posted this to document my experience with this new radiator. It is a great improvement over an open system and the workmanship on the radiator is very nice.