Car Components Cooling Systems 

Replacing a water pump

This is the water pump and drive layout found on most cars. The pump is mounted on the front of the engine and is driven by a belt which also drives the alternator. Water pumps wear out through age, through lack of lubrication on older types — which need greasing — or because the drive belt is too tight. A worn pump may leak around the spindle, in which case there are leak trails down the front of the engine and a slow loss of coolant. The pump may also…

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Car Components Cooling Systems 

Replacing core plugs

Two cup-type core plugs are visible in the block of this engine, under the manifold mounting points. Core plugs are also known as expansion plugs, welch plugs and sealing discs – a point to remember when buying one. The plugs are set in various places around the engine block and cylinder head. Their purpose is to seal holes left in the block and head when those components were cast. They also provide weak points which can give way under the pressure of expanding coolant if the engine freezes or overheats….

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Car Components Cooling Systems 

How to flush an engine radiator

Flush the water through until it runs out clear. Over a period of years, sediment builds up in a car’s cooling system even if antifreeze containing corrosion inhibitors is left in all year round. Eventually the sediment will start to obstruct the water passages in the radiator and engine. Such obstruction causes overheating of the engine which, if it becomes severe, can lead to engine seizure. If your engine is overheating and you have eliminated other possible causes, such as leaks (See Adjusting the static timing), the water passages are…

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Car Components Cooling Systems 

Checking heater and ventilator output

A typical heating and ventilating system, with heater ducts to the windscreen and to the front foot-wells. The plenum chamber is a box fitted on the bulkhead beneath the windscreen. It takes in fresh air from a grille on the outside of the car. Inside the chamber, movable flaps connected by cables to the heating and ventilation controls of the car divide and direct the air to the different parts of the interior. Incoming air is warmed by passing it over the fins of a small radiator, called a matrix,…

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Car Components Cooling Systems 

Checking for coolant leaks

Check the core plugs in the side of the cylinder block. Check all hose connections for tightness, but ensure that the clips are not cutting into the rubber. Look along the hose for cracks, especially at points where the hose is flexed by engine movement. Inspect the radiator seams for splits, also the catch tank and its pipe. Watch for leaks at the water-pump bearings and from the pump gasket. Check the thermostat housing for cracks, and the housing gasket for leaks. A rising temperature gauge, a pool of coolant…

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Car Components Cooling Systems 

Checking and topping up car antifreeze coolant

The radiator contains piping through which the coolant circulates, losing heat. The thermostat is typically a spring-loaded valve that opens and closes according to the temperature of the coolant. A good-quality antifreeze of the ethylene-glycol type, with full anticorrosive additives, should be left undisturbed in the cooling system for about three years — summer and winter. After that time, flush the system (See How to flush an engine radiator) and replace the coolant with fresh antifreeze mixture. Do not drain the system during summer and replace the mixture with water…

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Car Components Cooling Systems 

Draining and refilling a fully sealed cooling system

Coolant in a sealed system does not evaporate to the atmosphere, and should never need topping up. Instead, a pressure cap is fitted to the system, and a tube leads from the top of the radiator to a glass, plastic or metal tank or container. Coolant which has expanded as the system warms up passes down the tube into this tank, and is drawn back into the radiator when it has cooled. The system is supposed to be maintenance-free, and is drained only when a hose or the coolant is…

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Car Components Cooling Systems 

Checking hoses and the radiator cap

Inspect them when the engine is cold. Any sign of wear or deterioration is a danger signal: the sudden loss of coolant from a burst hose can result in rapid overheating and a seized engine. A worn or damaged hose should be replaced as soon as possible. Before this can be done, you need to drain the cooling system. Remove the radiator cap and open the radiator drain tap. If there is no tap, disconnect the bottom hose. If the coolant contains antifreeze that you wish to use again, drain…

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Car Components Cooling Systems 

How to remove a car radiator

On most modern cars the radiator has four side mountings and a top and bottom hose. The electric fan may be bolted to a fan cowl and enclosed, particularly on some transverse-engined cars where the radiator is mounted at the side of the engine bay. The damage is impossible for a home mechanic to repair, and usually the radiator must be replaced. Aluminium does not dissipate heat as well as copper, so there have to be more fins on the core, which is therefore easily clogged by dirt thrown up…

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Car Components Cooling Systems 

How to replace a car thermostat

In most cars the thermostat is placed under a housing near the water pump on the cylinder head; the housing is connected directly to the top radiator hose. In a few cars the thermostat is housed near the bottom hose. Test the thermostat quickly by starting the engine from cold. Put your hand on the radiator or top hose keep clear of the fan. If the thermostat works properly, the hose will stay fairly cool for a few minutes, then will quickly warm up. If the hose warms gradually from…

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