Ask the Mechanic
WHAT CAUSES OVERHEATING?
My car tends to overheat. What could be the problem? — Stephen
Hello Stephen, there are several causes of vehicle engine overheating such as leakage of coolant, failure of coolant hoses, blockage of the thermostat and radiator by corrosion and mineral deposits, failure of cooling fans, leaking radiator or water pump failure. Generally, overheating of vehicles is when the heat produced during engine running is above the normal operating temperature (85-100 degrees centigrade). Engine overheating should be of concern because it may interrupt your busy schedule in town or holiday trip when you see white steam and hot coolant gushing from under your bonnet or your engine stops suddenly.
Besides the interruption, engine overheating causes serious damage to cooling, lubrication and combustion system components such as gaskets, hoses and seals. In severe overheating episodes, more damage is occasioned to the cylinder head, pistons, piston rings or even the engine block. To prevent engine overheating, one must avoid or look out for the factors that lead to it.
Engine coolant condition and level: Coolant is the fluid that flows around the engine taking away heat and lubricating or preventing corrosion and blockage of the important cooling system components such as the water pump, thermostat, hoses and radiator. Coolant is designed with additives and ingredients that give it a higher boiling point to be able to help cool the engine. Coolant also has corrosion inhibitors as well as lubricant molecules. These help to maintain the cooling system components mentioned above. Coolant fluids age due to heating and use and should be renewed with a 50/50 concentrate or premixed solution after two years or a long life drain interval specified by the manufacturer. Coolant may leak due to a damaged hose, radiator or expansion tank. Coolant levels should be regularly monitored before you start the engine. Coolant leaks can be observed on cooling system components or the parking floor.
Water pump failure: This component helps to circulate water around the engine. Excessive corrosion buildup or lack of lubricant due to failure to service coolant will damage the water pump. This causes overheating.
Radiator and engine fans: These two components work together to lower coolant and engine temperatures. Corrosion caused by old coolant causes a leak or blockage in the radiator or failure of the cooling fans. This will affect the ability of these two components to cool the engine or keep it running at normal operating temperatures.
Thermostat: This helps to regulate coolant flow into the engine at particular temperatures. When it fails due to corrosion buildup, coolant will not be able to flow around the engine when its needed to cool it hence causing overheating.
Hoses and pipes: These transport coolant and can be blocked or damaged by corrosion or age. When they restrict coolant flow or leak the coolant, the engine will overheat.
Blocked heater core and vacuum lock: Corrosion buildup due to delayed coolant service can block the heat exchanger and prevent engine cooling. On the other hand, a leak in the cooling system can lead to a buildup of vacuum.
Low engine oil levels: Engine oil also helps to cool the engine as it lubricates and cleans hot fast-moving components. When the engine oil level is low, that will contribute to overheating.
WHY IS MY CAR VIBRATING?
Hello Paul, I have a 2001 Toyota Corolla which tends to vibrate when idling. New engine mountings have not solved the problem. What could it be?
- Derrick
Hello Derrick, your 2001 Toyota Corolla is experiencing reduced engine performance and power. It is easy to misdiagnose the cause of a vibrating sensation in a car as damaged engine mountings, which cause a similar sensation. That is why the new engine mountings have not helped.
Reduced car engine performance is usually caused by one or two of the following; reduced fuel pressure, restricted air intake system, dirty or faulty throttle potentiometer, blocked or damaged catalytic convertor or bad engine management sensors. Fuel pressure is reduced when you have a weak fuel pump, restricted or clogged fuel filter and dirty fuel injectors. An inspection of the fuel system to ensure that important components such as the fuel pump and injectors work well. A replacement of the long life fuel filter will improve fuel system cleanliness, fuel pressure and engine performance. This will reduce the vibration during idling.
A restricted air intake system and dirty or faulty throttle potentiometrecan reduce engine performance and power. A clogged air cleaner element, leaking or loose air intake pipe will reduce air required to achieve ample burning of fuel during combustion. A dirty or faulty throttle potentiometer will not allow adequate mixture of fuel and air. This reduces engine performance.
Replacing the air filter on time will resolve air intake cleanliness. A blocked or damaged catalytic convertor will restrict exhaust emission flow while the engine management computer will detune the engine. Faulty engine management oxygen and air flow sensors will also cause engine detuning if they are faulty. A computer diagnosis will help confirm all this.
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