Why is my car overheating?

It’s definitely not a good sign if your car’s temperature gauge is creeping into the red, or you’re seeing steam pouring out from under the bonnet. An overheating engine can leave you stranded, cause serious damage, and rack up a pretty hefty repair bill. You might be thinking “why is my car overheating?” but a more important question you should be asking is “what should I do if my car is overheating?”. Luckily, we’re going to cover it all!  

Coolant: Low, Leaking, or Just Missing 

Coolant is your engine’s main cooling agent. It circulates through the engine, absorbs heat, and dumps that heat in the radiator. If levels are low, or if there’s a leak, the engine can’t stay cool. 

Quick check: Once the engine is completely cool, check the reservoir. If it’s empty or below minimum, top it up with the right coolant mix and get it checked for leaks ASAP. Topping up is a temporary fix - if it’s vanishing regularly, something’s leaking. 

Faulty Water Pump 

If your coolant levels are fine, the next thing to look at is the water pump. This keeps coolant circulating around the engine. If it fails, whether through wear, a belt issue, or a blockage, coolant can't flow, and heat builds up fast. 

What to look for: Leaking coolant near the front of the engine, strange whining noises, or overheating at random times. This needs garage attention. 

Blocked or Damaged Radiator 

The radiator’s job is to release heat from the coolant. But if it’s clogged, cracked, or the fan isn’t working, the heat stays trapped in the system. 

Signs: Overheating especially in slow traffic, or visible gunk or debris around the radiator. It might need a flush or repair. 

Broken Thermostat or Temperature Sensor 

A stuck thermostat can block coolant flow entirely. Worse still, a faulty sensor might tell your engine it’s cool when it’s not, or panic it into thinking it’s overheating when it’s fine. 

Good news: If it's a sensor issue, you’ll often get a false alarm. Bad news? If it’s the other way around, you won’t know until it’s too late. But our technicians can run diagnostics to confirm. 

Low Engine Oil 

Oil doesn’t just lubricate; it helps carry heat away from the engine. Low oil = more friction = more heat. 

Fix: Check the dipstick. If it’s low, top it up and investigate why as it might be burning oil or leaking. 

Extreme Weather or Traffic Conditions 

Hot days, long drives at high RPMs, or crawling in traffic can all stress the cooling system - especially if it’s already underperforming. 

Top tip: If you’re overheating in traffic, open your windows and turn the heater on full blast. It’ll help draw heat away from the engine. Sweaty? Yes. But it might save your engine. 

What Should You Do If It Overheats? 

1. Pull over safely and switch off the engine. 
2. Let it cool down before opening the bonnet. 
3. Check coolant level through the reservoir (don’t open the cap if it’s hot!). 
4. Call us or head to your nearest garage. 

Overheating isn’t something to ignore. It can turn into major engine damage if you keep driving. If in doubt, play it safe and get it checked. A small issue now beats a massive bill later.