Components
Water pump (engine-driven or electric), thermostat (opens ~190°F), radiator + cap, fans (mechanical or electric), heater core, hoses, coolant + reservoir.
Overheating destroys engines faster than almost anything. Knowing the cooling system top to bottom is mandatory.
Most overheats aren't the water pump — they're a stuck thermostat, air pocket, or failing fan. Diagnose in order, not by guess.
Water pump (engine-driven or electric), thermostat (opens ~190°F), radiator + cap, fans (mechanical or electric), heater core, hoses, coolant + reservoir.
Stuck-closed thermostat (overheats), stuck-open (slow warm-up, MPG hit), water-pump weep, radiator clog, head-gasket failure (white smoke + coolant loss).
1) Verify coolant level + condition. 2) Test cap. 3) Verify thermostat opens. 4) Verify fans. 5) Pressure-test for leaks. 6) Block test for combustion gases. 7) Replace pump only after confirming.
Most modern OAT coolant lasts 100K mi / 5 yr. Old IAT (green) needs flush every 30K mi / 2 yr.