Thursday February 20 2014

Why does it take long to start in the morning?

By Paul Kangazi

I have a Nissan Terrano with a diesel engine. Lately, it takes long to start in the morning. What could be the problem?

Knowledge about your recent service history and current mileage would be useful. Assuming that your Terrano has the TD27 engine and you have recently replaced the diesel and air filter, a good technician will have to check your engine glow plugs (heater plugs) and make sure they all heat up adequately and are supplied with power during ignition. Check the little mesh filter on the intake hose of the fuel injector, if it is clogged with deposits it reduces fuel pressure.

My Mitsubishi Pajero made in 2002 with a diesel engine at mileage 190,000km fails to start in the morning or after being parked for six hours. You can try it 15 times before it starts. However, when it starts it stutters while emitting white smoke before stabilising. The battery is new and I have just replaced the battery and starter motor. Surprisingly after the engine warming up it can always start right away. What is the problem?
Bob Asiimwe.

During cold engine start, the function of glow plugs is to provide additional energy for the start cycle. Before the start of the engine, the glow plug is energised and the glow tube heats up to more than 800 °C. This heat improves the engine’s ability to cold-start considerably. The glow plug’s heat development also optimises the combustion so that the development of smoke and other emissions is reduced. No wonder during warm starts you do not experience the hard start, engine hesitation or excessive white smoke of unburnt fuel. Replace the glow plugs and you should be fine. Make sure you buy genuine ones because counterfeits will disappoint you.

I drive a 1998 Mercedes C200. When I shift into drive the vehicle jerks violently before moving. A few days ago it got worse, gear shifts are rough and delayed. What do you suggest I do?

Automatic transmissions contain mechanical systems, hydraulic systems, electrical systems and computer controls, all working in tandem. The mechanical systems include planetary gears that are engaged by the brake band friction with the help of automatic transmission fluid - ATF (viscous coupling). This fluid also helps to cool down the hot transmission chambers. The flow of ATF is facilitated by the electro hydraulic valve body whose solenoids (electric hydraulic gate valves) get electrical signals from the engine computer to release ATF to the appropriate gear set.

Therefore the condition and quantity of your automatic transmission fluid is vital for its good performance. You need a qualified technician to inspect your gearbox ATF using a special Mercedes ATF workshop dipstick. The colour and smell of this oil will tell whether its due to renew or not. Good oil should have a light clear or bright red colour. However, if the ATF is dirty and has a strong burnt smell it will be a sign of internal mechanical damage. Before carrying out an oil change it would be appropriate to carry out a computer diagnosis to rule out electronic failure due to damaged circuits or valve body solenoids.
You will also need able to check the operational status of your torque converter. If these components are okay replace the gearbox filter and pan gasket as well as the ATF. The Mercedes transmission service procedure is delicate and should involve draining the torque converter. In total you need eight litres of ATF.

My Range Rover Vogue has been emitting white smoke and a strange smell out of the air conditioner vents for a few days. At first I thought the car was overheating but it is not. The temperature gauge is normal and coolant level okay. What could be causing this strange happening?

You must check your air conditioning evaporator for leaks, this component is fitted under your Range Rover dashboard. A car air conditioning (AC)system works by evaporating the AC coolant inside it thereby absorbing heat. The evaporated AC coolant is pumped outside of the system and compressed to make it liquefy and give up its heat before returning to be evaporated again. When the evaporator develops a leak due to corrosion it lets off a sweet smell with a white mist. Sometimes it leaks this coolant to the floor. Accessing or dismantling the evaporator requires a qualified fitter and air conditioning technician.