The most efficient tractor engine will utilize approximately 35% of its energy into useful actions of driving, plowing, pulling, transporting and other farm duties. The excess 65% of energy produced will be lost in the form of sound energy, heat energy, radiant energy, vibrations, and friction.
A sufficiently cooled engine, and its counterpart, a sufficiently hot engine, are both necessary for optimum tractor engine performance. An over cooled engine can cause excessive damage to the engine components. Pistons and liners are designed to maintain very specific and minute clearances.
An over cooled engine will have its liners cooler than the hot pistons. The aluminum pistons typically expand faster than the steel based liners, and therefore, there will be scarring between the two surfaces. This damages the pistons, piston rings, and liner surface.
An excessively hot engine will cause all internal components to expand beyond normal tolerances, producing loose components, and burnt tractor engine parts. This is a phenomenon that is referred to as a "shot" engine or "seized" engine by mechanics. The tractor radiator removes excessive heat from the engine. The coolant that is circulating through the engine is allowed to be cooled via the tractor radiator.
The thermostats aids in this cooling process by preventing heated coolant from leaving the engine during the startup phase when the engine is cold, and allowing coolant to flow through the radiator when the engine temperature is above design temperature limits. The tractor radiator can be manufactured from aluminum or copper or alloys of aluminum or copper. Aluminum or copper is used as both have a high heat capacity, which is the capability to absorb and release a large amount of heat very easily.
The tractor radiator basically has rows of tubes, and onto these tubes are attached thin strips of metal. The coolant is forced through the tubes the water pump. Typically, the coolant flows from the top of the radiator, downwards through the tubes, and back into the engine block. Specially designed radiator hoses perform these high temperature connections between the engine and the radiator.
Onto these rows of metal tubes, are fitted thin strips of identical or similar metal. This effectively increases the surface area of the tubes, allowing the heat form the coolant to travel by conduction to the fins. The fins are typically designed as fins per inch. The 8N Ford tractor radiator and the David Brown radiator model 990 has eight (8) fins per inch, the Allis Chalmers radiator for the D17 has seven (7) fins per inch, the John Deere radiator for model 3020 has ten (10) fins per inch.
The other main component of the cooling system is the radiator cap. This serves to maintain a high pressure in the radiator, thus preventing the coolant from boiling, and it acts like a pressure relieve valve releasing coolant to the reservoir when hot, and pulling coolant into the engine when cold.