Cooling
Radiator Blocked or Damaged — Symptoms and Solutions
A blocked or damaged radiator causes overheating, especially at low speeds. Debris, corrosion, and impact damage are common causes.
The radiator dissipates heat from the coolant into the air. When its internal passages become blocked by sludge, rust, or hard water deposits, coolant flow is restricted and the engine runs hotter than normal — particularly at low speeds or when idling in traffic. External damage from stone impacts can crush cooling fins and reduce airflow. A leaking radiator will leave coolant puddles and cause the temperature to rise quickly. A coolant flush may clear mild blockages, but if the radiator is heavily corroded, leaking, or the fins are too badly damaged, replacement is the only reliable fix.
Key takeaways
- Overheating in traffic or at low speeds often points to a blocked or damaged radiator
- Stone impacts crush cooling fins and reduce heat dissipation efficiency
- Flushing can remove mild sludge, but corroded or leaking radiators need replacement
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