Maintaining your radiator

Increasingly, the radiator is also being called upon to maintain the automatic transmission's temperature and even to deal with the heat load in the engine's oil.

To keep the engine at a safe temperature, coolant is pumped through the engine's cooling passages, collecting heat as it goes. The coolant then leaves the engine via a (radiator) hose and travels to the radiator where it passes through a series of finned tubes. The fins are to increase the surface area of the tube to allow the heat to radiate away, hence the name. The cooled coolant is then returned to the engine via another hose to repeat the cycle.

Radiators are remarkably reliable considering the environment they work in. They are regularly exposed to internal temperatures that can range from below zero to well in excess of 100 C and operating pressures that can exceed 100kpa. But that isn't to say that radiators are immune to problems. In fact like any other part of the car, they need to be maintained to ensure trouble free service. This includes changing coolants at the designated intervals and the use of the appropriate coolant for the application.


From an owner's point of view, radiator maintenance is usually limited to ensuring that dirt, leaves or grass does not restrict airflow through the fins. Unrestricted airflow is important as it is the air travelling through the fins and around the tubes that removes the heat from the coolant. No matter how good the radiator, it can't work efficiently without proper airflow. Such debris can usually be washed from the fins by training water from a garden hose through the fins from the engine side of the radiator. Obviously, the engine should be cold and not running when you do this.

If your car is fitted with air conditioning 

It will most likely have what looks like a small, thin radiator in front of the engine's radiator. This is the air conditioner condenser and it removes heat from the air conditioning system in much the same way the radiator does for the engine. It's important that you check that there is no build up of debris in front of the radiator or the condenser, or between the two, as this can affect the efficiency of both.

Cleaning the tubes of the radiator

More serious maintenance involves cleaning the tubes of the radiator to ensure coolant flows freely. This is a job that requires the services of a specialist and necessitates the removal of one of the radiator's tanks so a metal rod can be passed through each tube to remove any blockages.

Blockages of this type can occur from inadequate servicing of the cooling system, but over time scale can build up in even well maintained cooling systems. Scale induced radiator blockages commonly occur after an engine has been overheated - as the overheating event can loosen scale formations in the engine block that become lodged in the radiator tubes.

Radiator problems 

Other common radiator problems include deterioration of core fins, corrosion of aluminium cores, impact damage, cracking of metal tanks and failure of plastic tanks.

Plastic tanks, particularly the top tank that is subjected to the greatest heat load, commonly deteriorate and need to be replaced once they reach around seven to eight years of age. Deteriorated plastic tanks can fail and quickly destroy an engine with little or no warning.

Other warning signs that should not be ignored are pools of coolant under the car after it has been parked, obvious water leaks and persistent coolant loss.

Replacing a radiator 

There are generally two options when its time to replace a radiator. One is to buy a new radiator and the other is to have your radiator re-cored. Re-cored, means taking the tanks and brackets from your old radiator and fitting them to a new core.

Like most automotive repairs it's important to shop around for the most cost effective option and to take professional advice as to the most suitable long-term repair for your car.