Car Overheating: Signs, Causes, and What to Do Next

When your car starts car overheating, a condition where the engine temperature rises beyond safe operating levels, often triggering warning lights or steam from the hood. Also known as engine overheating, it’s one of the most urgent problems you can face behind the wheel. It doesn’t happen out of nowhere. It’s usually the result of something smaller going wrong for weeks — a slow leak, a dirty radiator, or a worn-out thermostat. Ignoring it can turn a $200 fix into a $2,000 engine rebuild.

The radiator, a key part of the cooling system that transfers heat from engine coolant to the air is often the first suspect. If it’s clogged with rust or debris, or if the tank has a tiny crack, coolant escapes and the engine cooks. A coolant leak, a loss of fluid from hoses, the water pump, or the radiator itself is another common cause. You might not see puddles right away — sometimes it’s just a slow drip that evaporates before it hits the ground. And if your coolant hasn’t been changed in years, it turns acidic and loses its ability to protect the engine.

It’s not just the radiator. The car radiator, the main component responsible for keeping engine temperature stable relies on the water pump, thermostat, and even the fan to work together. A broken fan clutch or a stuck thermostat can block coolant flow, even if the radiator looks fine. And yes — low oil levels can also contribute. Oil helps cool parts of the engine too. If it’s too low or too dirty, extra heat builds up.

What does overheating feel like? The temperature gauge spikes. You might smell something sweet — that’s antifreeze burning. Steam might come from under the hood. Or your car might just lose power, sputter, and refuse to start after you turn it off. If this happens, pull over. Don’t keep driving. Let it cool. Then check the coolant tank — but only when it’s cold. Opening it while hot can spray boiling fluid everywhere.

Most of the posts below come from real repair jobs we’ve done in Stevenage. We’ve seen cars with cracked radiators from road debris, thermostats that stuck shut after five years, and hoses that cracked from old age. Some drivers thought a top-up of coolant was enough. It wasn’t. Others ignored the warning light for weeks. They paid for it.

Below, you’ll find clear guides on how to spot radiator problems before they turn into disasters, what to check if your car overheats on the motorway, and how to tell if your cooling system is holding up — or about to fail. No fluff. Just what you need to know to keep your engine alive and avoid a tow truck bill.