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Ask the mechanic : Why does my car overheat?
Ovearheating of a car can be caused by different reasons, however, you should look at the radiator caps as well. COURTESY PHOTO
Greetings Paul, I drive a 1997 Toyota RAV4 with a 3SFE engine. It was a reliable car until it developed an overheating problem. It starts boiling over even when the temperature is 90 degrees centigrade. My mechanic says the cooling fans, water pump, radiator, thermostat and cylinder head gasket are okay. What should we check?
Jimmy
Jimmy, overheating of your car engine can be caused by one of the following: faulty cooling fans, defective thermostat, leaking radiator or hoses, damaged water pump or warped cylinder head gasket and a faulty radiator cap. It seems your mechanic has ruled out most of the above causes. I strongly suggest that your mechanic inspects the radiator cap to rule out failure. The car engine’s radiator is a heat exchanger which transfers excess heat from the engine coolant fluid into the air. When coolant fluid overheats it expands, this makes it pressurised. When the coolant enters the radiator, it’s pressure increases. The radiator cap works as a release valve designed to open at a specific pressure point. When coolant pressure exceeds 15 psi, the valve on the radiator cap opens to release excess heat and coolant fluid to the expansion tanks on either side of radiator. When the radiator cools, coolant in the expansion tanks is sucked back into the cooling system. When the radiator cap fails, the engine coolant pressure relief and control fails. This causes instantaneous overheating. Radiator caps usually fail as a result of corrosion damage when you don’t change your coolant every two years following recommended guidelines and quantities.. That should fix the problem.
Hello Paul, I plan to buy an Ipsum next month. Please advise me if it is a good choice for a family of six people. I will appreciate any information regarding fuel consumption, service and stability. Thanks James
The Toyota Ipsum is a seven seater multipurpose vehicle produced in two generations between 1995-2001 and 2001- 2009. The first generation Ipsum was produced with 1.8 and 2.0 litre petrol engine as well as the 2.4 litre diesel engine. The second generation Ipsum was produced with the 2.0 and 2.4 litre petrol as well as the 2.0 litre D4D turbo diesel engines. The commonly sold Toyota Ipsum is the 1995 petrol 2.0 litre engine or the 2001 petrol 2.4 litre engine. The newer model is 12cm longer than its predecessor with 19cm of additional cabin length to allow seven adults a little more leg room.
The 1997 Ipsum’s 2.0 litre petrol 3S FE engine is simpler to repair, cheaper and easier to maintain. The 2001 Ipsum 2.4 litre petrol 2AZ FE requires maintenance using higher grade engine oil blended with detergent additives to protect its sensitive variable valve timing system. The 2001 Ipsum 2.4 litre engine gives a smooth, refined and responsive performance. It is better matched to the body weight of the Ipsum but will cover one kilometre less per litre of petrol. The 1995 Ipsum 2.0 litre petrol engine delivers 94 kilowatts of power and a fuel economy result of 11.1 km per litre. The more powerful 2001 Ipsum 2.4 litre delivers 118 kilowatts of engine power and 12 km per litre fuel economy.
The older 1995 Ipsum handles reasonably well on our multi terrain because of its length and reasonable ground clearance thanks to its strut type and coil spring front suspension combined with the rear suspension torsion beam and coil springs. The 2001 model comes with an improved electronic yaw control mechanism and the TEMS electronically adjusted suspension system all of which help to realign and adjust the suspension of the Ipsum. These facilities make the 2001 Ipsum a lot more stable and attractive to speedy drivers. Anti-locking brakes, side impact beams, child seat isofix harness, pretensioning seat belts, driver and passenger airbags are some of the many safety features on both Ipsum models. The 2001 model offers additional safety and control with electronic brake distribution, vehicle stability and traction control which enhance driver handling and occupant safety when driving fast on wet, slippery terrain.
Hello Paul, why should I replace my car engine timing belt and how often? My mechanic has recommended that we change the timing belt on my recently acquired Toyota Ipsum but it seems to be costly.
Kevin
Hello Kevin, I commend your mechanic for paying attention to a very important car maintenance detail often ignored. The timing belt (T Belt) is an integral component of many internal combustion vehicle engines. If it fails, your engine will most likely suffer severe and costly damage. The rubber timing belt synchronizes the engine’s fast moving components to allow engine combustion (fuel burn) while avoiding collision and damage. During an engine combustion cycle, the crankshaft and camshaft rotate fast to facilitate upward and downward movement of engine pistons which provide drive to the car wheels via the transmission. The intake valves allow in the fuel air mixture which is compressed by the upward cycle of the piston for combustion and the ensuing explosion which causes the downward piston cycle. The exhaust valves release the burnt gas. The T belt ensures that these components are run in a predetermined synchronized sequence to avoid collision of the bigger pistons and smaller valves. It is recommended by most car manufacturers to replace the engine T belt before or at 100,000 kilometres. The rubber compounds used to build the timing belt are expected to fail due to wear and tear caused by exposure to heat and friction. Most car manufacturers indicate T Belt replacement intervals in the user manual or on stickers attached to the timing case. When we buy used cars we ought to look out for the current mileage with view to replacing the timing belt. In case you are uncertain about the mileage, you can carry out a precautionary T Belt replacement. Some post 1990s vehicles have timing chains which are less likely to fail like the rubber timing belt and are therefore not eligible for routine change. However, timing chain systems are known to fail or get damaged if an engine suffers from poor lubrication due to oil sludge build up or use of counterfeit engine oils and delayed oil change service. You can prevent this damage by using engine oils blended with anti-sludge detergent additives and corrosion inhibitors.
Ask the mechanic
By Paul Kaganzi
0772316145
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