An overheating engine is one of the few car problems where what you do in the next five minutes genuinely changes the size of the bill. Most faults get gradually worse. This one can go from a leaking hose to a cracked cylinder head in the time it takes to finish your drive home.

So we’ll start with what to do, and explain the causes after.

If the gauge is climbing right now

1. Turn the A/C off and the heat on full. It’s miserable in July, but the heater core pulls heat out of the engine and can buy you a few minutes.
2. Pull over somewhere safe and shut the engine off. Don’t try to make it to the next town. Don’t try to make it home.
3. Open the hood if you can do it safely — it helps the heat escape. If there’s steam, wait until it stops.
4. Do not open the rad cap or the coolant reservoir. More on this below, because it matters.
5. Let it cool for at least 30 minutes before you touch anything.
6. Call us. Tell us what the gauge did and whether you saw steam — we’ll tell you whether it’s safe to bring in or whether it needs a tow.

Seriously: leave the rad cap alone

A hot cooling system is pressurised. That’s by design — pressure raises the boiling point of the coolant. Opening the cap while it’s hot releases that pressure instantly, and the coolant flashes to steam and comes out of the opening.

People get badly scalded doing this every summer. Face, hands, forearms. It is the single most dangerous thing an ordinary driver can do at the roadside, and it’s usually done by someone trying to help.

Wait until the engine is cool enough that you can rest your hand on the upper rad hose comfortably. If you’re not sure, wait longer.

What’s actually going wrong

Overheating always comes down to the same thing — the system isn’t moving enough heat out of the engine. The reason it isn’t is usually one of these:

Low coolant, because it’s leaking. The most common cause by a distance. Coolant doesn’t get used up; if the level is low, it went somewhere. Hoses, the radiator itself, the water pump, or a gasket.

A stuck thermostat. The thermostat opens to let coolant flow to the radiator once the engine is warm. When it sticks shut, the coolant never reaches the radiator and the temperature climbs fast.

A failing water pump. It’s what circulates the coolant. If it isn’t pumping, nothing else in the system matters.

The radiator isn’t shedding heat. Either it’s blocked internally with corrosion and scale, or the cooling fan isn’t running, or the fins are packed with road debris.

A head gasket. The one nobody wants. It can cause overheating, and overheating can cause it — which is exactly why driving on a hot engine is such a bad trade.

The order matters here: the first four are ordinary repairs. The fifth is a major one. Very often the difference between them is whether the vehicle got shut off promptly.

Warning signs before it gets that far

• The temperature gauge sitting higher than it usually does, even if it never reaches the red
• Topping up coolant more than once
• A green, orange or pink puddle where you park
• A sweet, syrupy smell after a drive
• The heater blowing cold, or only working at speed

That last one catches people out. If your heat has quit, that’s a cooling system symptom — the heater runs off the same coolant. It’s worth getting looked at before it turns into an overheating problem on a hot day.

It happens in winter too

Overheating feels like a summer problem, and mostly it is. But a thermostat stuck open is a winter fault — the engine never reaches proper operating temperature, your heat is lukewarm, and fuel economy suffers.

And coolant that’s past its life stops protecting against freezing. A block that freezes is a far worse outcome than one that runs hot. Both directions are the same system, which is why we’d rather check it before the season turns than after.

Common questions

Can I just top it up with water and keep going?

In a genuine emergency, water is better than running dry — but only once the engine has cooled, and only to get the vehicle somewhere safe. Water doesn’t have the freeze protection or the corrosion inhibitors coolant does, and topping up doesn’t fix the leak that emptied it.

Can I drive it if it cools back down?

We’d rather you didn’t. It’ll almost certainly heat up again, and the second time does more damage than the first. If it’s a short distance and the gauge is normal, drive with the heat on and watch it constantly. If in doubt, tow it — a tow is cheaper than a cylinder head.

How much does it cost to fix?

It depends entirely on what failed — a hose and a thermostat are a world away from a head gasket. That’s the honest answer, and it’s why the diagnosis comes first. Give us a call and we’ll talk it through.

My gauge is fine but I keep adding coolant

Then you have a leak, and you’re currently keeping ahead of it. Get it found while it’s small. Coolant leaks don’t heal.

Get it looked at

If your temperature gauge is doing something new, if you’re topping up coolant, or if the heat has gone cold, bring it in. We’ll pressure test the system to find where it’s actually going rather than guessing, and tell you what it needs.

Rick’s Automotive has been keeping Oxford County on the road for 20 years. See our cooling system and radiator service, read up on your car’s fluids and what each one does, or book an appointment.