Ask the Mechanic
WHY DOES MY CAR’S UPPER ENGINE MAKE A LOT OF NOISE?
Hello Paul, I have driven my Pajero iO (2000 model, 4G94 engine) for nine years now. Of late, there is a clunking noise from the engine. A mechanic said it is the hydraulic tapperts or engine oil I need to change. The engine has never been overhauled and I always use reliable engine oil. What could actually be causing this noise and how can I solve it. Is it time to overhaul the engine?
Hello Denis, upper engine noise in your Mitsubishi 4G94 engine is most likely caused by dirty hydraulic lash adjusters also known as hydraulic valve lifters. This component is a cylinder which is located between the engine camshaft and cylinder valves. The valve lifters are crucial for the timely opening and of intake and exhaust valves and maintaining valve clearance in the engine. When they make noise, it means the other important valve train components will not work well.
This will not only affect engine performance but could potentially cause severe engine damage if left unattended to for a long time. This problem is usually caused by accumulation of dirt or sludge in the valve train and hydraulic valve lifters or oil starvation due to compromised engine oil supply pressure. Rather than change oil viscosity as you have done, it is crucial to check the engine oil pressure.
Check or clean the oil pickup tube below the engine and consider replacing the oil pump if found worn out or damaged. The push rods and valve lifters should be inspected and cleaned if found dirty or replaced if they are excessively worn out due to oil starvation. Thicker viscosity oil would be required if the engine was leaking (burning oil) and needed more internal sealing. Stick to lighter viscosity engine oil which should climb up or build oil pressure faster to clean and protect the upper engine or valve train components as soon as you start.
CAN I SWAP TO A SMALLER ENGINE CC FUEL INJECTORS TO REDUCE FUEL CONSUMPTION?
I recently put a 7K, EU engine graded 1800cc in my Toyota Liteace Van thinking I would get better mileage in terms of KM/Litre (fuel consumption). Is it advisable to change my fuel injector with any compatible injectors of a lower grade engine such as 1300cc or 1500cc and still receive a better performance in mileage, fuel consumption without losing power? The 7K engine gives me a mileage of 7.5km per litre of petrol. Before insulation, I was getting 8km per litre with a 3Y engine. Any advice will be appreciated.
Hello Tenywa, it is not a good idea to swap fuel injectors of a smaller Toyota engine cubic capacity (cc) say from 1800cc to 1300cc in the attempt to get better fuel mileage (economy). All modern electronic fuel injection engines are designed to run on specific amounts of fuel per mili-second and this is programmed in their specific engine control units (engine management systems).
When you attempt to fit smaller engine size fuel injectors (if they fit at all) you will cause damage to your engine by running it on a lean fuel condition. A lean engine running condition is one where the fuel air ratio delivered has less fuel than it should have. This condition will not only reduce engine performance but will also cause potentially harmful engine overheating, excessive cylinder knock and damage to critical components such as valves and piston rings. There is no fuel gain from reducing fuel delivered to your engine yet you are carrying the same car body weight of your Liteace.
Engine body weight ratio is also critical for fuel economy. A similar situation is where some motorists believe that a smaller engine capacity will always give you better fuel economy, regardless of car size. That is why an 1800cc engine on your Liteace may actually consume as much fuel as a 1500cc engine because the smaller engine will be running on higher rev bands (will work harder) than the bigger engine which has a better engine body weight ratio.
There are ways you can improve your Liteace fuel economy. Use efficient fuels that clean fuel wasting dirt from your fuel injectors to improve fuel economy and performance.
These fuels reduce upper cylinder friction, which makes your engine run lighter and use less fuel. Service and tune your engine so that it runs lighter and more efficiently. Make sure your tyre treads are good since better traction helps your engine use less energy or fuel.
Correctly inflate your tyres as they will have less fuel demanding rolling resistance. Also, avoid aggressive acceleration and harsh braking since these keep your transmission in fuel guzzling low gears. In traffic jam, switch off your engine as you are going nowhere. Avoid overloading your car and use momentum to drive your car by easing off the accelerator when driving downhill.
MY CAR WHEELS WOBBLE AT SPEEDS BETWEEN 80-100 KPH
Hello Paul, I recently bought a second hand PASSO 2006 model. Acceleration between 80-100km/hr is marked by wobbling/vibrating from the front. Acceleration below 80km/hr or above 100km/hr is smooth. I have tried wheel alignment, balancing and engine mountings among others but in vain. What could the problem be?
Hello Roland, vibrating, shaking or wobbly tyres at speeds between 80-100kph can be quite unnerving and dangerous because it affects handling and safety when you are driving fast or on a rainy day. This situation can be caused by wrong wheel alignment or unbalanced tyres. In your case, you have already ticked these two boxes.
There are other potential causes of vibrating or wobbling tyres you ought to inspect and fix or rule out. Unevenly worn out tyres is your next box to tick. Tyres will unevenly wear out if your car has poor wheel alignment, worn out suspension bushes or you often drive it with over or under inflated tyres. Occasionally, a faulty ABS brake system or an incident of excessively hard braking can cause uneven wear of your tyre tread surface. There are obvious and visible signs of uneven tyre wear that can be seen during inspection such as excessive wear of the inner, outer or centre parts of a tyre.
Scalloped or cupped tyre surfaces are another sign of uneven wear. This is caused by worn out shock absorbers or bent suspension components. Swelling of the inner or outer surface of the tyre can cause uneven wheel rotation or wobble. Other potential culprits of wheel wobble and shaking at certain speeds are worn out hub bearings (which have a noticeable muffled rumbling sound during vibration) and tie rod ends (which would be seen during wheel alignment).
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