An overheating car can quickly turn a routine drive into a stressful situation. Whether you're stuck in Sydney traffic or heading out on a long road trip, seeing the temperature gauge spike or steam billow from under the bonnet is never a good sign. But what causes a car to overheat in the first place?

Why is your car overheating?

Low coolant levels, a leaking radiator, a broken water pump, or a faulty thermostat can all prevent the system from working properly. Blockages in the radiator or hoses can also restrict coolant flow. Sometimes, overheating can be triggered by external factors such as driving in extreme heat, towing a heavy load, or idling for long periods without adequate airflow. No matter the cause, an overheating engine needs immediate attention to avoid serious (and costly) damage. Knowing the right steps to take (and what to avoid) can help protect your car and keep you safe.

The Do’s and Don’ts when your car is overheating

Do:

• Pull over safely: As soon as you notice the temperature gauge rising into the red or steam coming from the engine, find a safe place to pull over and turn off the engine. Continuing to drive could cause irreversible damage.
• Switch off the air con and turn on the heater: This might sound odd, but turning on the heater can help draw excess heat away from the engine and into the cabin, buying you a bit more time if you're not yet able to stop.
• Check coolant levels (once it's safe): After allowing the engine to cool down completely (which can take 30 minutes or more), check the coolant level in the overflow tank. If it's low, you may be able to top it up with coolant or water as a temporary measure.
• Call for help: If you're unsure about what’s caused the issue or whether it’s safe to drive, take a step back and call roadside assistance. They can inspect the situation and help you avoid further damage.

Don’t:

• Don’t keep driving: If your engine is overheating, pushing on can warp or crack vital components like the cylinder head. It’s not worth the risk.
• Don’t open the radiator cap while hot: Opening the radiator cap while the engine is still hot can result in scalding steam or hot coolant erupting under pressure. Always wait until everything has cooled down.
• Don’t rely solely on water: While water can help in an emergency, it's not a long-term replacement for coolant, which contains additives that protect your engine and radiator.
• Don’t ignore the problem: Even if the car seems fine after cooling down, the root cause of the overheating must be diagnosed and fixed. Otherwise, the issue is likely to return – possibly worse than before.

Step-by-step: what to do when your car overheats

1. Watch for warning signs: Keep an eye on the temperature gauge, warning lights, and steam from under the bonnet. If any appear, take action quickly.
2. Pull over safely: Find a secure place to stop, preferably away from traffic. If you must drive a short distance to stop safely, turn on the heater at full blast to help remove heat from the engine bay. Turn off the engine immediately to prevent further heat build-up.
3. Wait for the engine to cool: Lift the bonnet slightly (if it's safe to) to allow air to circulate, but wait at least 30 minutes before touching anything under the bonnet.
4. Check coolant levels: Once the engine has cooled completely, check the coolant reservoir. If it's empty or low, top it up to the marked level. Avoid opening the radiator cap unless you're sure it's cool.
5. Look for obvious leaks: Check underneath the car for signs of leaking coolant, and inspect hoses and connections if visible.
6. Restart cautiously: If you’ve topped up the coolant and there are no visible leaks, you may try restarting the engine. Keep a close eye on the temperature gauge as you drive.
7. Call for help: Visit a mechanic or call roadside assistance as soon as possible. Even if the engine appears fine, it's important to identify what caused the overheating to prevent it from happening again.

An overheating car is never something to take lightly. Acting quickly, knowing what to do (and what not to do), and getting professional help can mean the difference between a simple repair and a major engine rebuild. Keep an eye on your coolant levels, maintain your vehicle’s cooling system, and stay calm in the heat of the moment. If you need a quick refresher on all things car fluids, here's how to check the fluid levels in your car, or check out our trusty tips and tricks.