Reply to "Radiator Choices - Cooling System Info"

Two dynamic laws to keep in mind: (1) Fluids (such as coolant) are not compressible ... only gases (such as air) are compressible. (2) Both fluids and gases will flow from a zone of higher pressure to a zone of lower pressure. Never the other way around.

The air space above the coolant in the header tank cannot exist at a pressure lower than pressure of the coolant pump suction. If it did, it would draw coolant away from the coolant pump and into the header tank! So .... the air can collect in the header tank because it is compressible, but the coolant in the header tank cannot be drawn out of the header tank any faster than coolant is flowing into the header tank.

The cooling system is a closed hydraulic system. Every ounce of coolant drawn from the header tank is replaced by the same amount of coolant entering the header tank. So, what is happening, the coolant in the header tank is constantly "turning-over" but the level in the tank remains the same. If you don't believe this, open the hood of your daily driver and observe the coolant level in that car's header tank while the engine is running. Most header tanks are manufactured from opaque plastic these days. If the cooling system's pressure cap (radiator cap) is not located on the radiator, but on a tank, that tank is a header tank. You can verify this by tracing the large hose connected to the bottom of the header tank. It should connect or "tee" into to a portion of the plumbing that connects to the cooling pump's suction. The cooling pump's suction is the lowest pressure zone of a cooling system. There should also be one or more smaller air vent hoses connecting to the header tank, attached at the other end to various points where air may collect in the cooling system ... such as the top of one of the radiator's tanks.

The header tank is a feature found in the cooling systems of most (if not all) modern cars and it has been used in racing cars as far back as I can remember. There's a lot of experience there. Every Pantera owner who has "admitted" to making the mod has reported good results. All I have done is explained how easy it is, using existing components, to modify the Pantera's cooling system to duplicate such a system. I believe its easy to convert the Pantera's cooling system because the Pantera's system was originally designed to be configured in that way.

Why do I believe this ... well the "system tank" was obviously manufactured to be a "de-gas tank", aka a swirl tank, due to the way in which the inlet and outlet nipples are configured. Here's the part where the light bulb should turn-on for the typical enthusiast ... a de-gas tank (such as the Pantera's "system tank") cannot function without a header tank! The header tank is needed because it is the low-pressure point of the cooling system where air can be plumbed and collected successfully. The Pantera's "expansion tank" was obviously intended to be a header tank! That explains why the connection on the bottom of the expansion tank is so large!