COOLING FAN

The cooling fan help to keep a constant flow of air moving past the radiator, particularly at slow speeds. The shroud fitted around the fan plays a big part in getting the most air flow through the radiator. Without it the air the fan tries to move past the radiator can simply be a wasted effort. There are two basic designs when it comes to the fan fitted to your defender. Either electric or belt driven. Electric cooling fans are found of later model 4WDs and also many engine conversions. One of the benefits of electric cooling fan is they can be mounted directly to the radiator and have no physical connection to the engine.

The most common belt driven fans have a viscous clutch hub that allows the fan to disengage from spinning when airflow isn’t in demand. Like at high speed and when the engine is could. As the engine temp rises, the viscous clutch locks the fan. Some early 4WDs fitted with belt driven fans have a direct drive hub that spins the fan at the same speed as the engine that all times. While it’s the simplest design, it robs the engine of power at touring speeds as the fan is constantly being driven.

Considered the heart of the system, the water pump circulates coolant through the entire system. In most cases, the water pump is bolted to the engine block in the front section of the casting. The water pumps heart a belt driven hub and shaft that drivers that internal impeller. Coolant is the drawn from the bottom radiator hose after being passing though the radiator and pumped through the engine and heater core, and back into the radiator. It’s fairly common for the radiator fans drive hub (for the belt driven fans) to be mounted to the water pump pulley.