Racing Cooling System Switches, Sensors & Relays

An internal combustion engine provides optimum performance and fuel consumption when operating within a narrow temperature range between 195 and 220 degrees of Fahrenheit, whereas, some racing engines can run even hotter. If the temperature goes down, the engine will lose its efficiency and, vise versa, a higher temperature may cause damage to the motor. To keep this under control is the job of the engine cooling system, which relies on different sensors to continuously monitor the temperature of the engine, and uses different switches and relays to operate the cooling fan and indicate the driver if the motor runs out of its normal temperature range.

Whether it is a gasoline or diesel engine, it has at least one sensor that measures the temperature of the engine. This sensor is called an engine coolant temperature sensor and is usually cut into the engine block. It determines the coolant temperature and sends the data to the control module. The ECU analyzes them and based on the engine temperature adjusts ignition timing and fuel injection if necessary, as well as activates the radiator fan if the engine is getting too hot. The information received from the sensor is also used to operate the temperature gauge on the dashboard, allowing the driver to visually monitor the temperature of the engine.

When the engine gets too hot, the ECU starts the cooling fan. In order to avoid a short circuit and damage to the control unit, the fan is operated via a relay. Those vehicles that do not have an ECU use an engine cooling fan switch to start the fan. This switch is cut into the radiator and is activated when the temperature of the coolant that flows through the radiator reaches a specific threshold. As soon as the antifreeze cools down to a specific predetermined level, the engine cooling fan switch breaks the circuit. It does not rely on the engine coolant temperature sensor, so it will work even if the sensor fails.