Thursday May 15 2014

Why won’t my car start?

A BMW3 series.  A reader, Shem Kiryowa has a similar car and

A BMW3 series. A reader, Shem Kiryowa has a similar car and he is experiencing starting problems. A number of issues may lead to this problem, including loss of coolant if the coolant hose is loose or damaged. FILE PHOTO 

By Paul Kaganzi

I switched off the engine but when I tried to start again it would not start. After about one hour, it started again and I drove again without any problem up to now! What could have been the problem?
Shem Kiryowa.

From your description of the incident I can tell that the hissing sound was probably escaping engine coolant under pressure. This may be a result of a torn or loose coolant hose, cracked radiator top, leaking water pump or thermostat housing. Coolant pressure build up in a vehicle engine or its escape will happen even before the car temperature gauge hits the red mark (over heating point).

Leaking or seeping coolant under pressure can be a sign that the engine cooling system has started overheating and needs to be checked.
You need a mechanic to check and confirm that your radiator blower fans run the different cooling stages. If they do not the engine will build pressure and overheat in slow traffic or when you drive fast. It is necessary to examine the BMW engine thermostat to look out for corrosion damage or leaks. The thermostat is housed in a plastic or enamel housing which can spring a leak if put under pressure especially if it is blocked.

A broken down water pump can cause the above symptoms as it does not deliver coolant fluid on time to cool the engine. Little wonder your car did not start easily after you switched it off briefly.

The overheating engine must have affected the magnetic hall effect of the engine crankshaft position (CKP) sensor.
The CKP sensor regulates the engine computer’s delivery of fuel which is probably what prevented the car from starting instantly until it cooled down. Driving short distances around town or from home to work may not reveal the above problem until you drive the car fast for a long distance or when you are in a traffic jam for a long while.

Thank you for the articles, in the Monitor newspaper as they are very educative. What is your take on Toyota Surf 2000 model using petrol? Is it a good car compared to a Nissan Terrano?
Allan Mpairwe

I will assume you are looking at the Toyota Surf (4Runner) with 3RZFE 2.7 litre petrol engine and the Nissan Terrano with the 3.0 litre turbo diesel engine. Both vehicles are sturdy and robust enough to take on any tough terrain. Terrano’s bigger 3.0 litre (2,953cc) diesel engine delivers almost the same power (113 kw/152hp @ 3,600rpm) as the 4Runner Surf’s smaller 2.7 litre (2,693cc) petrol engine (112kw/125hp @4,800rpm) because they both have DOHC valve trains with 16 valves which guarantees prompt power delivery.

Terrano will tow or carry bigger loads while using less fuel because its engine torque (304nm @1,600rpm) is higher than Surf’s (240nm@4,000RPM) and achieves its peak power at lower engine revolutions. Terrano’s superior fuel economy is also helped by the fact that diesel fuel gives you more kilometres to the litre. Terrano’s fuel consumption on the highway is 13.5 km/litre while Surf covers 7.1km/litre.

Terrano’s off road prowess is guaranteed by its front double wishbone suspension and rear De Dion solid tubular beam non- independent suspension and higher ground clearance. On tarmac and reasonable off road turf the 4 Runner Surf’s unibody single shell construction and lower roof profile gives it a better centre of gravity and road holding during high speed cornering and maneuvering. While the Surf’s longer cabin offers more luggage room its seating, legroom and headroom are more cramped up compared to Terrano which is more spacious.

Surf and Terrano have reasonable comfort amenities such as CD music, air conditioning and power windows. Safety is enhanced in both cars by the dual airbags and ABS brakes. Reliability of the Surf and Terrano is good as they are built strong and both have appointed dealers to guarantee parts sales.
However, Terrano parts are generally more expensive while Surf has better availability of new and used parts to suit one’s budget. Whereas Terrano has a lower price tag compared to Surf, its resale value is poorer.

Hello thank you for guiding us always on car issues. I want to know: when the OD light is on, does it mean that you have engaged over drive or it should be off for you to say that you have engaged overdrive.

The Over Drive is disengaged (off) when you see the ‘O/D OFF’ light displayed. This means the facility is switched off. When you switch on the Over Drive (O/D) by flicking the switch on your gear lever, the ‘O/D OFF’ warning lamp on your dash board will stop displaying.