Ask the Mechanic


Hello Paul, I bought a locally used BMW 3 series. Everything seems okay but the front seat belts are loose and do not seem to grip. What can I do to repair them?


Hello George, car seatbelts exist for your safety and are not a mere traffic regulation to satisfy traffic police. Seatbelts are meant to save lives and prevent severe injuries. Travelling without wearing a seatbelt or using nonfunctioning seatbelts makes you vulnerable to injury or death during accidents.

When a vehicle is in motion, the passengers and loads in the vehicle continue travelling in the same direction, at the same speed, even when the vehicle suddenly turns or comes to a standstill during roll over, side impact or forward collision. This will often result in severe injury or fatality (death) of the passengers in the affected vehicle.

Seatbelts are devices designed to harness and secure passengers in vehicles. They also work in four main ways to protect vehicle occupants by preventing injury during collision or sudden stop. Seatbelts also secure you to the seat to prevent secondary impact from moving objects inside the car such as panels during collision, sudden stop or roll over. They also keep passengers harnessed to their seats and protected by supplementary restraint systems such as airbags or roll over protection systems (rally cars or roofless convertibles) and head restraint support and whiplash prevention (such as the Mercedes Neck pro).

Seatbelts prevent passengers from being tossed out of a vehicle during any of the above accident situations. They come in three main designs, the lap belts, three point sash seat belts (most common) and five point seatbelt harness for rally car drivers.

Basic seatbelt designs have a floor to frame mounted buckle where the seatbelt harness is secured. Therefore, those mounted to the seats (like our matatu PSVs) are insecure and hazardous. The seat belt harness works with a tandem pendulum retracting device which is designed to respond to sudden change of direction or movement (during sudden stop, impact or roll over) by locking to taunt the harness belt over the passenger.

Newer vehicles are designed with smart seatbelt pretensioning devices which are triggered off when they detect impending collision or sudden change of direction to tension the belt across the passenger and reduce forward movement and possible injury. The loose seatbelts on your BMW may have damaged retracting and pretensioning systems which may not be repairable if the tensioning spring is damaged. Find a good BMW mechanic to check why the belt retracting mechanism has failed and help make the decision to replace them.


Hello Paul, my sister has a Toyota Wish whose oil levels keep going down. What could be the cause?


Hello Alice, It is good to top up engine oil whenever the level drops. However it is not good to make it a habit. It is also important to service engine oil on time because its protective and performance enhancing additives will have aged and become less effective at the recommended drain interval or indicated next service mileage. We should note how often and how much we need to top up the engine oil. 

It is normal for an old engine (15 years and above) to consume half a litre of engine oil over the 5,000km service interval. This small amount of oil is usually lost through the engine crank case ventilation system. If you need to top up one litre or more, then your car engine has an oil leak or it burns oil internally. An engine oil leak can be external at one of these engine seals such as those at the top valve cover, spark plugs, crankshaft, camshaft or engine sump below the engine.

An aged and faulty crank case ventilation valve oil separator can also cause oil leakage. The external oil leaks are easier and less costly to fix. Internal engine oil leaks are more costly because they are costlier as they involve engine overhaul or replacement of parts such as piston rings to stop internal oil leakage and burning. Signs of internal oil leakage are increased exhaust smoke, poor fuel economy and engine performance.

A good garage can carry out a compression test to confirm this. A short term solution is to service with mono grade SAE 40 engine oil, which has better engine sealing properties and thicker viscosity.

However this is not a permanent fix as most of the post 2,000 engines with variable valve timing systems require extra  cleaning and performance enhancing multi-grade mineral or semi synthetic engine oils for the smooth operation of the VVTi solenoid.

Use of the correct engine oil grade and a reputable product will prevent engine leakage as described above.


Hello Paul, my Toyota Vista Ardeo is taking longer to change gear and its power is reduced, especially in hilly areas. What could be the cause?


Hello Ivan, it sounds like your Toyota Vista is experiencing loss of engine power while driving uphill. The common cause of this problem is fuel supply restriction, usually due to a dirty long-life (petrol) fuel filter.

Driving uphill puts an energy (fuel) demand on your engine, if fuel pressure is low then you will experience reduced performance.

It is a little bit like you running uphill while hungry. A restricted fuel filter can lead to damage of the fuel pump which has to work extra hard to pump fuel through the clogged filter.

This fuel filter is in a canister attached to the fuel pump located in the petrol tank. You need a qualified mechanic to safely and properly change that filter.

Buy the filter from an established Toyota parts outlet to avoid a faulty counterfeit. If your car has reached 100,000kms, consider servicing its automatic gearbox with Toyota TIV gearbox oil or Dexron III equivalent.

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