22nd June 2021

How To Stop Your Classic Car From Overheating This Summer

Summer is here, and, like every other season, it brings its own distinctive challenges for the classic car owner

One of the biggest headaches on hot days in June, July and August is how to prevent overheating both under the bonnet and behind the wheel. 

Your classic is likely to have been built before electric fans, extreme weather testing and maybe even traffic jams. This makes older models more susceptible to overheating.

So how can you and your car keep cool? 

There are many ways you can lower your risk of breakdown callouts or potential expensive trips to the garage. Here are some of them…

Regular checks

Vigilance is vital. This means regular checks of belts, hoses, radiators, fans among others. They could save you hundreds of pounds before the first leaves start falling off the trees. 

Your vehicle’s temperature gauge can be your best ally and early-warning system. This will tell you if your old engine is operating a tad hotter than normal.

The trick is not to ignore your gauge’s tell-tale clues. Engines are built to operate hot for best efficiency. But this isn’t to the degree that they become overheated and harm components through overpressure or coolant loss

So get into the habit of making preventative maintenance and checks. These take far less time than having to get your car towed away to the garage or waiting for the breakdown repair van to arrive.


Think of a car overheating and most of us will probably think of radiators as the likely cause. These are magnets for grime and bugs.

Such accumulation can impair your classic’s efficiency by creating blockages. But a simple pressure-nozzled garden hose can put paid to these in minutes.

Want to check blockages inside? Just disconnect your radiator’s lower hose before running water into the top.

If the water exits and enters the radiator at similar speeds then you’re OK.

If not, simply back-flush your radiator to open any calling tubes that are gunged up. Maybe consider getting yourself a modern radiator fitted.

This will make your cooling system less prone to malfunctioning. 

But first of all, why get a brand-new radiator if your engine block is clogged? 

Ensure that your cooling system is in good order first. Newer aluminium radiators have a greater capacity, making them OK to be fitted in muscle and older cars alike.

But they won’t fit every older car.

Radiator caps

A change of radiator cap could make all the difference. You can buy caps four times as heavy and resilient as a bog-standard 4lb one.

Radiator fans

Get this changed and you could treat your radiator to more airflow.

There are plenty of types to choice from, from flex fans to electric pusher ones which are thermostatically controlled.

Hoses and belts

These should be replaced at five-year intervals, regardless of how often you may drive.

Cracked and frayed belts should be replaced at once. Cracked and swollen hoses should also be disposed with.


This is vital to your quest to keep cool this summer. It regulates your car coolant’s circulation via its cooling system.

Older thermostats which should open up in the warmer months can stay shut.

This will make your classic car heat up faster than virtually anything else.

Head gaskets

This seemingly innocuous component can end up costing you hundreds if it blows.

So keep checking your fluids.

Failure to do so could result in coolant leaking from the cooling system.

Keep an eye out for oil in your coolant to see if this is happening.

Freeze plugs

It may seem odd to be talking about a component designed to safeguard your pride and joy from freezing now the summer’s here.

But freeze plugs can erode and overheat your car by leaking water into your cooling system.

So locate the whereabouts of your freeze/core plugs. They’re almost always either side of your car’s engine block.

Keep checking them.

The signs are usually obvious to even the most basic DIY mechanic.

Heater cores

Watch out for leaking coolant in the heater box.

Heater cores are notorious for rusting.

If the problems are none of the above then your likely gremlin may rest with things not connected with your cooling system.

Oil coolers

A sure way to keep your car feeling cool, especially if you’re a racing regular who likes to test the revs.

And finally…

One useful trick of the trade is to put exhaust wrap on all exhaust components (except mufflers and catalytic converters) and headers. 

It means that less exhaust component-generated heat goes beneath your bonnet.

Exhaust wrap reduces the density of exhaust gasses, meaning they can escape more quickly.

Do you have any extra tips not mentioned here? Let us know in the comments below!

Nice article, full of useful tips. I would like you to add some information on flushing out rust and grime from the system. Thanks

DomBlack, 03/06/2021