Water pump: Circulates coolant through the engine and radiator. Driven by the serpentine belt.
Thermostat: Stays closed when cold (keeps coolant in the engine to warm up quickly); opens at operating temperature to allow flow to the radiator.
Radiator: Heat exchanger — transfers heat from coolant to air. Hot coolant enters at the top, exits cooled at the bottom.
Radiator cap: Pressurizes the system (~13–16 psi), which raises coolant's boiling point.
Antifreeze/Coolant: Ethylene glycol + water mix. Lowers freezing point, raises boiling point. Never use water alone in freezing temperatures — it will freeze and crack the block.
Cooling fan: Pulls air through the radiator at low speeds or when stopped.