Car Radiator Problems: Signs, Causes, and What to Do

Car Owl

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Summary

• Overheating is the main warning sign: If your temperature gauge rises, pull over and let the engine cool.
• Radiator replacement costs £200-£500: Including parts and labour at most UK garages.
• Regular coolant checks prevent problems: Low coolant is often the first sign of a leak. Read our coolant guide for more.

Your radiator is vital to your engine's health. If it is not working properly, your engine can overheat and suffer serious damage. Here is what to look for and what to do.

Signs of Radiator Problems

• Engine overheating: The temperature gauge goes into the red zone.
• Coolant leak: Green, pink, or orange fluid under the car.
• Steam from the bonnet: Coolant is boiling and escaping as steam.
• Low coolant warning: The level keeps dropping even after you top up.
• Discoloured coolant: Brown or oily coolant suggests contamination.
• Cold heater: If the cabin heater blows cold air, coolant may not be circulating properly.

Common Causes of Radiator Failure

• Corrosion: Over time, the radiator corrodes from the inside, especially if coolant is not changed regularly.
• Physical damage: Road debris or minor impacts can puncture the radiator.
• Blocked fins: Dirt, leaves, and insects block airflow through the radiator.
• Faulty thermostat: A stuck thermostat prevents coolant from reaching the radiator.
• Failed water pump: The pump circulates coolant. If it fails, the radiator cannot do its job.
• Head gasket failure: Exhaust gases can enter the cooling system, causing overheating.

Repair Costs in the UK

What to Do If Your Car Overheats

1. Pull over safely as soon as you can.
2. Turn off the engine and let it cool for at least 30 minutes.
3. Do not open the radiator cap while the engine is hot. Boiling coolant can cause serious burns.
4. Check the coolant level once the engine is cool. Top up if needed.
5. Call for help if the temperature rises again when you restart.

Driving with an overheating engine can warp the cylinder head or crack the engine block. These repairs cost thousands. Always stop and deal with overheating immediately.

Preventing Radiator Problems

• Check your coolant level regularly.
• Have the coolant changed every 2-5 years (check your owner's manual).
• Keep the radiator fins clear of debris.
• Get your cooling system checked during each service.

Final Thoughts

Radiator problems are serious but preventable. Keep your coolant topped up, get it changed on schedule, and act fast if you see the temperature rising.

Regular servicing catches cooling system issues early. See our car servicing guide for a full maintenance schedule.

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