Car radiators are the most common cause of car breakdowns in the UAE, and yet they are fantastically simple to maintain.

When an engine is running, its pistons are moving up and down the bores at anywhere between 1500rpm at idle to 8000rpm at flat-out - this creates heat and friction. The only way to keep them cool is to have water flowing through canals in the engine block – enter the radiator.

The radiator keeps your car’s engine cool, and it’s important to look after it. Signs that all is not well under the bonnet will begin with the water temperature gauge. It should be running at no more than 90 degrees Celsius. If it starts to rise then you should stop. Another sign is burning smells and steam coming from under the bonnet.

Here is what could cause an over-heated radiator.

WARNING - Never open the radiator cap when the engine is hot. You risk being scalded. Always wait for the engine to cool down.


1. Low coolant level


Coolant, a mixture of antifreeze (ethylene glycol) and water is a fluid pumped around the engine and kept cool with the help of the radiator. The purpose of this antifreeze is to keep the water in the radiator from freezing in cold temperatures and, more relevant to the UAE, boiling over in the warmer climates.

A low coolant level in the radiator is one of the major reasons for overheating in vehicles. The drop in level could be due to a variety of reasons like a leak in your head gasket – which is a serious problem - or the heater-core..

It is advised to renew the coolant every time the radiator is serviced. Ideally this is to be done annually. You should check your coolant level at least once a month – topping it up with water is acceptable.

2. Clogged radiator


Common causes for a clogged radiator are dirt, dead insects and loose debris such as stones. These will block the airflow through the radiator resulting in it overheating. Open the bonnet and you can usually see this clearly.

If there is nothing plainly visible, it could be an internal clog. Scan the surface of the radiator for cold spots using an infrared thermostat if you have one. If you don’t have one, open the radiator cap when the car is cool and then check the fluid and the radiator for any brown discolouration, or suspended contaminates in the coolant like floating dirt.

3. Heat exchanger materials


Traditionally radiators were made using copper and brass cores. But cost-efficient and weight-saving aluminium cores using plastic tanksare slowly replacing them. The reason for this change is that aluminium radiators cool much better than the copper-brass ones. The rate of heat transfer in aluminium is impressive among common metals.

If you have an older car with copper and brass core plumbing, then the car’s age could be the issue. Newer cars won’t be too affected.

4. Radiator cap


A malfunctioning radiator cap causes radiator overheating, a very common and overlooked cause. If the radiator cap has not been screwed on correctly then coolant could be leaking.

The cap also helps maintain the correct water pressure, and if it’s not sitting correctly, the pressure is compromised.

5. Thermostat

The thermostat is a valve, and is a key component of the radiator. If the thermostat is stuck closed, the hot water in the system can’t escape back to the radiator to be cooled. This results in overheating.

Thermostats are relatively simple to replace and are the most common causes of overheating.

Read more tips on how to prevent a car breakdown here.