The Ford Barn

Marshall V. Daut · 08-10-2025, 05:00 PM

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

08-10-2025, 05:00 PM	#2
Marshall V. Daut Senior Member Join Date: Apr 2011 Location: Davenport, Iowa Posts: 2,894	Re: Overheating 1930 Model A Ford Coupe 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