Question: I have a Toyota RAV4 D-4D with 135 000 km on the clock. Besides numerous other problems that I have had with the car, my main concern is that, when I pull away in first gear and accelerate, the exhaust tailpipe emits a massive cloud of black smoke. When I change into second gear, the same thing happens. A Toyota dealer told me the injectors would have to be replaced at a cost of R15 000. At this moment, I cannot afford it. If I carry on driving the car as is, will any further damage occur? Is it common that injectors pack up at such a low mileage? The car has been filled with 50 ppm diesel for 90 per cent of its life.
SPERO ROCKAS – By email
Answer: We would not expect an injector replacement at 135 000 km if only good-quality fuel was used. Remember that a diesel engine without a diesel particulate filter will always emit some soot. The smoke you are seeing is due to incomplete/poor combustion of the fuel-air mixture, which leads to the formation of diesel particulates. There are many reasons for increased soot during combustion, including dirty/damaged injectors, low injection pressure, low compression, air-intake restriction, burning oil if the rings are worn or poor-quality fuel.
The other effects of poor diesel combustion are:
• High fuel consumption;
• Low power;
• Hard starting;
• Rough running of the engine;
• The increase of fuel in oil levels (as some unburned fuel will make its way past the rings) can lead to engine damage or even engine runaway if the oil is not regularly changed.
We recommend that you monitor your fuel and oil consumption, and service the vehicle regularly. Run high-quality diesel for a few tanks (containing a standard cleaning agent) and see if the situation improves. If not, you’ll have to take the expensive route.
