Car Problems Guide
Why Is My Car Overheating?
An overheating engine is one of the more serious warning signs a vehicle can give. Continuing to drive an overheating vehicle can cause significant engine damage. Here's what commonly causes overheating and what to do if it happens.
Quick Answer
A car overheats when the cooling system can't remove heat from the engine fast enough. Common causes include low coolant level, a coolant leak, a failed thermostat, a clogged or damaged radiator, a failed water pump, or cooling fan problems. Do not continue driving an overheating vehicle — pull over safely and let the engine cool before investigating.
What to Do If Your Car Starts Overheating
If the temperature gauge rises into the red zone or an overheating warning light comes on, turn off the air conditioning immediately — it adds load to the engine. If the temperature continues to rise, pull over safely and turn off the engine. Do not open the hood immediately — wait at least 15 minutes for the engine to cool before checking anything. Never open the radiator cap on a hot engine. Continuing to drive an overheating vehicle risks warped cylinder heads, a blown head gasket, or more serious engine damage.
Low Coolant Level
Coolant (antifreeze) is the fluid that carries heat away from the engine. If the coolant level is low, the cooling system can't do its job effectively. Low coolant can be caused by a slow leak, a more significant leak, or coolant that has been consumed over time. Topping off the coolant is a temporary measure — if the level is consistently low, there's a leak that needs to be found and repaired.
Coolant Leaks
Coolant can leak externally — from hoses, the radiator, the water pump, or connections — or internally, through a failed head gasket into the combustion chamber or oil passages. External leaks are often visible as puddles under the vehicle or staining on components. Internal leaks are less obvious and can cause white smoke from the exhaust, a sweet smell, or coolant mixing with the oil. Both types require repair.
Thermostat Failure
The thermostat regulates coolant flow between the engine and the radiator. A thermostat that's stuck closed prevents coolant from flowing to the radiator, causing the engine to overheat quickly. A thermostat stuck open can cause the engine to run too cool, affecting fuel economy and performance. A failed thermostat is one of the more common and straightforward cooling system repairs.
Radiator and Water Pump Issues
The radiator dissipates heat from the coolant as air passes through it. A clogged, damaged, or leaking radiator reduces cooling capacity. The water pump circulates coolant through the system — a failed water pump means coolant isn't moving, and the engine overheats. Both components are part of a cooling system inspection.
Cooling Fan Problems
At low speeds and when stopped, the engine relies on electric cooling fans to pull air through the radiator. If a cooling fan fails or a fan relay fails, the engine can overheat in traffic or at idle even if the cooling system is otherwise functioning. This type of overheating often appears at low speeds or when idling and may resolve at highway speeds where airflow through the radiator is sufficient.
Overheating can have multiple causes, and some causes — like a head gasket failure — can be expensive if the vehicle is driven after the warning signs appear. We don't diagnose cooling system problems remotely. A cooling system inspection at any of our locations is the right starting point.
Reviewed by the Stop & Go Car Care automotive team.
COOLING SYSTEM INSPECTION — ALL THREE LOCATIONS
If your vehicle has been overheating or running hot, bring it in for an inspection. Choose the location nearest you.