Overheating 1930 Model A Ford Coupe

[Marshall V. Daut]

Do you have a split radiator cap, such as a Moto-Meter or a Flying Quail? If so, when the coolant in the radiator is pushed at high speeds, it flows faster through the top radiator tank than the core can handle. This excess water then forces its way through the most convenient and easy exit place, meaning between the two halves of the specialty radiator caps. The engine is not overheating; it's just pumping out the heated and expanding water. This is a very common situation that is usually attributed to engine overheating.
Place a standard plain radiator cap on the radiator instead of the specialty two-piece cap and see if that stops the coolant exit. Also, do not overfill the top radiator tank. Only fill the top tank until the water is just above the core. More than that and the heated coolant will find a way to exit.
Marshall

[Synchro909]

Originally Posted by Marshall V. Daut

Do you have a split radiator cap, such as a Moto-Meter or a Flying Quail? If so, when the coolant in the radiator is pushed at high speeds, it flows faster through the top radiator tank than the core can handle. This excess water then forces its way through the most convenient and easy exit place, meaning between the two halves of the specialty radiator caps. The engine is not overheating; it's just pumping out the heated and expanding water. This is a very common situation that is usually attributed to engine overheating.
Place a standard plain radiator cap on the radiator instead of the specialty two-piece cap and see if that stops the coolant exit. Also, do not overfill the top radiator tank. Only fill the top tank until the water is just above the core. More than that and the heated coolant will find a way to exit.
Marshall

Unless the volume of the coolant is increased by say, exhaust gasses or steam, the only water that can flow though the top tank comes from the engine, which in turn gets its water from the bottom of the radiator.
In other words, because the volume of coolant is constant it is not possible for the pump to put more water into the top tank than has been drawn through the radiator core.