The GMC Jimmy radiator is designed to efficiently shed engine heat. The thermostat, the radiator, and the water pump all work in conjunction to keep the engine operating at the optimal temperature, which is achieved by maintaining the coolant fluid at approximately 200 degrees Fahrenheit. The radiator of the Jimmy, like most mass-produced automobile radiators, is essentially a system of aluminum tubes with hundreds of thin, flat aluminum plates or fins attached along their coiled length.

The cooling fluid, ideally a combination of antifreeze and distilled water, flows through the tubes. Heat is conducted through the metal of the tubes to the aluminum fins, where airflow dissipates the heat.

The thermostat controls flow to the radiator. When the coolant is cold, the radiator is bypassed and the coolant flows back to the engine to be heated again. Once the coolant reaches a sufficient temperature, the thermostat opens, and coolant is free to flow into the radiator. Constant opening and closing of the thermostat aperture keeps the temperature within the optimum range. Changing the coolant at regular, manufacturer-specified intervals is crucial to keeping the fluid flowing through the GMC Jimmy radiator, and indeed, all radiators. Coolant should be changed at a minimum of every two years, regardless of usage. The Jimmy is based on the S10 pickup chassis and can see some light off road usage, which translates to more frequent maintenance. Inspect the radiator regularly for bent and missing fins. Any debris, such as rocks and leaves, should be cleaned out, as they will disrupt airflow and will prevent the radiator from operating efficiently. Any frontal collision, however minor, means that the radiator should be closely inspected for damage, as a coolant leak will leave you stranded on the road or trail.A leaky radiator should be replaced, not plugged.