[Car Tips] How to prevent engine overheating in hot summer

☀️ Editor's thoughts: What's special about Hong Kong's "heat killer" in summer?

☀️ Hong Kong Summer Engine Overheating Prevention Checklist

In Hong Kong, the summer temperature (especially in July and August) often hovers between 32°C and 35°C , with the ground temperature even exceeding 50°C . Furthermore:

• Traffic congestion → Slow speeds put heavy strain on the cooling fan.
• There are many slopes along the hiking trail → Going uphill requires a high speed and generates more heat than on a flat road.
• Heat island effect caused by high-rise buildings → In urban areas such as Causeway Bay and Mong Kok, the heat is difficult to dissipate.
• Keeping the air conditioner on all the time → The operation of the air conditioner compressor will increase the engine load and heat.

The result is this: even if your car has no obvious mechanical issues, the wrong driving style in Hong Kong summers can send the water temperature soaring into the danger zone.

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🔍 Why does the engine overheat?

When the engine is running, fuel combustion generates a large amount of heat. Under normal circumstances, this heat is dissipated through the coolant system, cooling fan, and engine oil lubrication . However, this system can become "overloaded" in the following situations:

1. Cooling system failure (insufficient coolant, water leakage, radiator aging)
2. Decreased water pump efficiency (aging, belt slippage)
3. Excessive external temperature + poor ventilation (crowding, heat island environment)
4. The engine is under high load for a long time (long uphill climb, with the air conditioner on and heavy load)

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🛡 Hong Kong summer tips for preventing engine overheating

1. Pre-trip inspection: Prevention is better than cure

• Check the coolant tank : the water level should be between MIN and MAX. It can be checked every two weeks in summer.
• Check the radiator cap rubber ring : poor sealing will lead to insufficient pressure and reduced cooling efficiency.
• Clean the dead insects and blade dust from the radiator : Long-distance driving on Hong Kong's coastal roads often encounters insects, which can block the radiator's airflow.
• Engine oil condition : Aged engine oil has poor heat dissipation performance, so the maintenance cycle can be shortened moderately in summer.

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2. Driving habits: reduce excess heat accumulation

• Do not hold the accelerator for a long time when idling in a traffic jam : idling heats up quickly, and low speeds dissipate heat poorly.
• Downshift moderately before going uphill : Keep the engine speed at around 2500-3000, which is beneficial to the efficient operation of the water pump.
• Never turn off the fan or air conditioner at high speed and then shut down the engine directly (pay special attention to turbocharged vehicles). Run the engine at idle speed for 1-2 minutes to allow the circulation to cool down.
• When waiting for someone, avoid idling the air conditioner for too long and open the window less often while waiting.

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3. Make good use of air conditioning and ventilation

• When turning on the air conditioner, start with external circulation, and switch to internal circulation after the temperature drops to reduce the fan load and heat dissipation pressure.
• In low-speed traffic, if the temperature inside the car is comfortable, you can turn off the air conditioning compressor and only turn on the blower to help reduce the load on the engine.
• Do not set the air conditioner to the lowest temperature + maximum air volume for a long time, as this will cause the compressor to operate at high load for a long time.

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4. Equipment inspection and upgrade

• Check the working condition of the cooling fan : if it is stuck or the speed is insufficient, it needs to be repaired immediately.
• Check the thermostat : A malfunction can cause the coolant to circulate abnormally, leading directly to overheating.
• High-performance coolant : It is a worthwhile investment for car owners who often drive long distances or on mountain roads.
• Installing an oil cooler (modification) : can effectively reduce the oil temperature in high temperature environment.

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5. Emergency supplies

• Spare coolant/distilled water : does not take up too much space and can be replenished in an emergency.
• High-temperature resistant gloves : In case you need to open the hood to check or connect pipes, you can prevent burns.
• Small spray bottle : Spraying the outside of the radiator to help cool it down can be done safely (but don't pour water directly on a hot engine!)

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🚨 What to do if you encounter overheating (Hong Kong traffic version)

• Stop immediately in a safe place (in the Cross-Harbour Tunnel and Eastern Cross-Harbour Tunnel, try to drive to the emergency lane)
• Do not open the water tank cap immediately! High-pressure steam may cause burns. Wait at least 30 minutes before checking.
• While waiting, you can open the car's hood to speed up heat dissipation.
• You can turn the heater up to maximum (even if it's very hot in the summer) and use the radiator to help cool the engine.

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💡 Editor's Summary

Hong Kong's summer isn't just hot outside; the road temperatures, salty and humid seaside air, and city congestion create a "triple threat" to engine overheating.
When I drive in summer, I must do the following:

• Check the water level before driving
• When washing the car, rinse the front of the radiator
• Downshifting on a mountain road
• Not turning on the air conditioner at high power or idling for long periods of time when stuck in traffic may seem like small things, but doing them over time will extend the lifespan and safety of your engine in Hong Kong's high temperature environment.