Overheating is one of the most common problems that occur in a car. If you observe very well you must see one or two cars that gets overheated while on the road. Before delving into some of the issues that can cause a car to overheat, let me give Nigerian drivers a very quick tip.

Once your car is overheating, the first thing to do is to pull over at a safe place and away from the path of traffic. Pull down the windows and turn the heater on and switch the fan to the highest level. This acts as an extra radiator inside your car. This will help bring down the temperature of the car. Now let’s see those things that can cause a car to overheat.

Air Flow Issues – Failure of the radiator fan and the condenser can cause your car to overheat. Most times dirt or some debris can block the condenser or fan and thereby prevent the circulation of air. The fan switch or fuse can also get blown. To make sure the overheating is not caused by any of these, check that the radiator fan is working. Make sure you don’t have any dirt wedged in-between the condenser and or radiator fan. If the fan is not working, check that the fan switch is properly plugged in. Look into the fuse box and locate the fan fuse. Check if the fuse is burnt and have it replaced with a fuse of the same rating.

Radiator Cap – The radiator cap performs two basic functions. First, it keeps pressure on the system measured in atmospheres (1 atm = 14.7 psi). The radiator cap has a rating. You will see the rating at the top of the cap. Some are rated 0.9 and others are rated 1.1 measured in atmospheres. radcapWhen changing your radiator cap, make sure the new one is of the same rating with the old. The second function of the radiator cap is that it regulates the coolant level. When you turn the cap, you will notice a rubber valve. This valve opens and allows the coolant to flow from the top of the radiator to the overflow tank when the cooling system is hot. When the cooling system is cold, the valve opens and allows the coolant to travel from the overflow tank back to the radiator. Overheating occurs when this valve is damaged. Radiator caps with damaged valves may allow coolant to flow to the overflow tank but will block the return path making the coolant not to return back to the radiator and thus causes overheating. To check that the radiator valve is working, check the coolant level of the overflow tank after a long commute and check it again after the engine must have cooled for some hours. An important safety tip – DO NOT TOUCH OR TAKE THE RADIATOR CAP OFF WHEN THE CAR IS OVERHEATING.

Thermostat – A Thermostat is a mechanical valve that maintains the temperature of the engine by regulating the flow of coolant within the engine. As the cylinders starts to fire, heat is generated which in turn is dissipated by coolant. ThermThe thermostat will stay closed until the coolant gets to a certain temperature which activates the thermostat to open slowly and allow coolant into the engine. Once the coolant flows into the engine, cooling the system, the thermostat slowly closes again. The cycle is repeated as the coolant gets heated up again.

There are two major problems associated with a thermostat. Stock closed and stock open. Stock closed thermostat causes overheating and happens when the coolant heats up but the thermostat could not open to allow coolant from the radiator into the engine thereby causing overheating. The easiest way to check for a stock closed thermostat is to touch the radiator hoses. In a normal working thermostat, both the upper and lower radiator hoses should feel warm to the hand. If the upper hose is hot and the lower hose is cool then the thermostat is stock closed. It simply means that coolant is not circulating in the system.

Coolant Leakage – Coolant leaks are the easiest problem to identify because the coolant may be seen dripping or seeping out from the leaky part. This is why the use of colored coolant is recommended instead of just ordinary water. This helps to easily identify the leak and distinguish the coolant from the water coming out of the air conditioning system. The coolant color may be red, green or orange.

Overheating can occur as a result of leakage in the cooling system which may come from the engine, radiator, hoses, water pump, manifold gasket, or heater core. In subsequent post, we will look at how to find and repair coolant leaks.

Trapped Air in the System – Trapped air the cooling system can cause the engine to overheat. Air can get into the cooling system whenever any part is opened for repair, servicing or replacement. When parts such as the radiator, thermostat, water pump, and hoses are worked on, there is a likelihood of air being trapped in the system. This air forms a bubble which prevents the normal and continuous flow of coolant in the system. Since air does not dissipate heat as can a liquid, the cooling system performs poorly. This problem can be taken care of by making sure to bleed the cooling system any time any of the aforementioned part was opened for servicing or repairs. We will discuss how to bleed the cooling system in later post.

There you have it. Any time your car overheats, make sure to check these 5 things that can cause your car to overheat and remember the quick fix in such a situation – turn up your heater and fan to the highest level to help dissipate the heat.

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