Explained: What Does a Car Radiator Do?

Anyone who’s driven a car will have at some point heard about its radiator, but unless you’re an experienced mechanic or know your way around an internal combustion engine, you might be wondering just what it actually does. Well, wonder no longer as Scrap Car Comparison’s latest instalment in our Car Care Guide answers that exact question.

How does a car radiator work? 

While the radiator attached to the wall of your living room is there to keep you warm in the colder months, the one you’ll find at the front of your car does the exact opposite. In your engine system, the radiator works alongside a thermometer, water pump and cooling fans to ensure that the engine continues to operate at the correct temperature – i.e. not too hot – and when the mercury peaks above the required level, pumps coolant around the entire system, eventually making its way to the radiator.

Once the coolant is in the radiator, the slatted design, which is designed in a way to increase the surface area, cools the liquid down, aided by the fans. It then works its way back towards the thermometer to start the entire process again.

How to fill a car radiator with water 

While early cars were often air-cooled, these days the vast majority of vehicles on the road are cooled down with water, so you’ll want to ensure that your car is suitably stocked up on H2O before you set off on a long journey.

However, don’t just fill it up with water alone. Here in Britain, we’re no strangers to inclement weather in winter (despite our apparent inability to cope on the roads when snow falls), and with water freezing below 0°C, there needs to be some additives to ensure you don’t try and drive away with a solid block of ice sitting in your engine bay. Enter antifreeze. The best ratio is a 50/50 split, but you can also buy pre-mixed antifreeze solutions, some of which are tailored to specific cars.

Now you’ve got your coolant mixture ready, ensure that your car is cold as serious injury can occur opening the radiator cap from the pressurised steam in both the radiator or the pipes. The cap should be easy to locate, as it will be sitting atop a large, transparent container that will have MIN-MAX markings running down the side of it. If pouring the water and antifreeze separately, then it does not matter which order you pour them in as they will mix once in the reservoir. It is important to note, however, that antifreeze is incredibly poisonous to animals, so ensure that none is spilt onto the ground during this process. Once all the liquid has been poured in – ensuring that the total amount reaches closer to the MAX markings than the MIN – tighten the radiator cap firmly and start up the engine. Allow it to idle for around 10 minutes, but keep your eye on the temperature gauge on the dashboard. If it sits around halfway, then you’ve done a good job and can carry on your merry way. 

Do all cars have radiators?

As previously mentioned, some early cars were air cooled, and as such do not have radiators as part of their internal gubbins. However, this has all-but died out now save for a handful of cars that retain their air-cooled heritage. Early Fiat 500s, Renault 2CVs, Volkswagen Beetles and Porsche 911s were all air-cooled, although their modern siblings have all since adopted water cooling methods and feature radiators.

However, radiators are beginning to show signs of being a thing of the past themselves with the advent of battery-electric vehicles and the push for more environmentally friendly modes of transport. Without an internal combustion engine to keep cool, there is no longer any need for radiators. This has also, inadvertently, created an easy method of identifying EVs on the road. For many years, the radiator grille at the front of a car had been a design feature, an easy way to identify each car manufacturer – BMW‘s twin-grilles (that seem to keep on growing), Jeep‘s slatted design and the Tom Selleck-style moustache of original Minis.

Now, though, designers are left with a gaping hole which used to be filled by their grilles, and it’s clear that not all of them know what to do with them. Ford‘s Mach-E does a good job, and Hyundai‘s ioniq does a good job of integrating the design into the overall feel of the car.

How to fix a leaking car radiator

A leaky radiator is one of the most common mechanical difficulties found within cars, and can be caused by a multitude of reasons. You’ll often see a pool of fluid underneath cars involved in head-on impacts as the radiator disperses all of the liquid within. Other causes can be down to worn parts such as hoses or pumps, a faulty radiator cap or even extremely cold temperatures. It can also be a sign of head gasket failure. 

The easiest way to fix a radiator leak is to take it to your nearest garage and let someone who knows what they’re doing have a go. As with all work under the bonnet, unless you know exactly what to do, there is a strong possibility that you could make things worse before you make them better, which will only serve to increase the bill when you eventually take it to the garage to have someone else both fix the original problem and undo your mistakes.

If you’re adamant that you want to do it yourself, however, then you will need to follow these steps:

  1. Check the entire system for swelling, collapsed hoses or any coolant crusting over on connections – beginning with the hoses themselves. Also look for any broken fins and cracks in the radiator casing itself.
  2. If you can’t find any obvious issues, a coolant pressure sensor can let you know if there are any faults in the system.
  3. Add radiator sealant to the engine while it is running but the coolant is still cold.
  4. If this still doesn’t fix the problem – remove the radiator.
  5. With the radiator removed, re-pressurise it using a specific radiator pressure kit and then submerge it in water. If any air bubbles are released it will identify leaks within the radiator itself.
  6. With the leaks identified, and the radiator dried out, apply an epoxy seal to the damaged areas.
  7. Repeat steps 5 and 6 as necessary.

Can a car radiator be repaired?

In most cases, simply applying an epoxy seal to damaged areas of the radiator should be sufficient enough to permanently fix any radiator leaks. However, each case will have its own nuances, and if you’re unsure whether your radiator is too damaged to be considered viable for repairs, it’s best to take it to a garage for an expert opinion before deciding whether to splash out on an entirely new radiator or carry out the repairs.

Get the best price for your car with Scrap Car Comparison

If your radiator is causing consistent problems or you seem to never be able to keep your temperatures down in your car, then perhaps it’s time to look elsewhere and find something new. That’s where Scrap Car Comparison comes in. No matter the age, condition or whatever else of your car, we’ll get you the very best price for it.

Get started today with our online quote generator, and we’ll provide you a value for your car in as little as 60 seconds, and with buyers all around the country, we can even come and collect the car from you, wherever you are, at no extra cost.

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