Engine Repair (A1)Question 8 of 120
Which cooling-system component regulates coolant flow based on engine temperature?
a.Water pump
b.Radiator cap
c.Heater core
d.Thermostat
Explanation
The thermostat stays closed until the engine reaches operating temperature, then opens to allow coolant to circulate through the radiator. A stuck-closed thermostat causes overheating; a stuck-open one causes slow warm-up and poor heater output. It is a common, inexpensive cause of temperature complaints.
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