Cooling The Flathead - Tech

The Flathead Ford motor is legendary in many ways, most of them good. But one downfall of this great motor has been cooling. Even in 1932, the first year of the Flathead V-8, Ford was fighting an overheating problem, leading to such rare items as the 25-louver hood. Over the years hot rodders have wrestled with overheating Flathead motors, and in fairness, cooling any hot rod motor was an issue.

The Flathead may be notorious for cooling problems, but it is just another motor, except for a couple of unique features. We will be referring to the 8BA (1949-53) and 59AB (1938-48). All Flatheads generate more heat because the exhaust gases spend more time exiting the block. The Ford V-8 employs two water pumps for cooling, so you actually have two cooling systems sharing a common reservoir known as the radiator. This unique cooling system has some interesting traits, let's take a look at them.

The newest U.S.-manufactured Flathead engine you can buy is 57 years old-that's 57 years of scale, rust, old sealant, and residue inside the engine. There was also the problem of casting sand leaching out of the castings and residing inside the block. We have heard of everything from sandblasting the inside of the block to "roll it around on the floor" to remove scale, but in the end few things can compare to a chemical bath. "Cooking" a block in a chemical hot stripping tank today removes rust and scale that could not be removed years ago and that's the first step toward cooling a Flathead or any vintage motor. Not only does this scale inhibit uniform water flow through the block, the scale also acts as an insulator, making it more difficult for heat transfer from the block to the coolant. Once the motor is clean, have the machine shop check it thoroughly for cracks using a Magnaflux type of examination.

If you're experiencing an overheating problem consider two things. First is a simple block test to see if you have a blown head gasket or worse, a cracked block. Cracked blocks account for a high number of the "impossible to cool" Flatheads because you may be introducing 1,100-degree combustion gases into the coolant, thereby super heating the coolant and introducing gases that cause additional hot spots. The test is a simple kit available from your NAPA store. Generally it's a blue liquid in a tube. The coolant is drawn into the tube with a bulb and the blue fluid turns green or yellow in the presence of exhaust gases. This is done with the engine at full operating temperature. If your engine runs cool at idle but gathers heat as speed increases, a block test should be performed. Remember it's entirely possible to have a cracked block, head, or bad head gasket and not have cross contamination between the coolant and oil.