Gavin,
I have a pre-millennium Toyota Prado 3.0 diesel turbo that just goes on forever. Even after 300,000kms, it starts first time every time, goes well and doesn’t belch smoke or burn oil, however, in recent months I have noticed a slight reduction in power and an increase in fuel consumption, even after its regular service. About 10 percent on both counts. Is this irreversible old age, and/or is there something I can do to extend its life and restore its youth?
Jack.
All vehicles suffer progressive loss of performance with age – through engine wear which reduces compression and the gradual degrading of other components in the system in a number of places along the whole drive train. The effects may have only just become noticeable to you, but they have been happening to some degree for much of your car’s life. If your car is used moderately and serviced diligently, it might continue to go well (though less-and-less optimally) for many more years as this ageing process continues. With an increasing number of repairs and some replacements, half-a-million kilometres is not unthinkable for cars like yours. Meanwhile, you could give it some 300,000km birthday presents to help it feel younger. After all, that distance equates to nearly eight times round the world!
If it is not burning any oil and the exhaust doesn’t have a hint of grey smoke when the engine is revved hard, the chances are the piston rings are in good enough condition, but you could have the compression tested to be sure. If it is not belching black smoke, there is probably nothing seriously wrong with the injectors, but fitting new injector nozzles could perk up the power and improve fuel economy. Injector overhauls and re-setting are best done on a professional test bench.
It is also worth ensuring the engine is “breathing” properly – a new air filter if the existing one is well used, and also a check and cleaning of the insides of the intercooler, which may be fouled with dirty oil, therefore restricting air flow. Prados also recommend a precautionary change of the timing belt at least every 100,000kms. Yours is due its third. Even if the belt is not about to break, the chances are that it has stretched slightly and no longer delivers the precision for optimum performance and fuel economy. Think, too, about when you last changed all the oils/fluids in the gearbox, the diffs, the power steering and the brakes. If you can’t remember when, add those to the birthday libation.
None of these measures will give a venerable old car the same performance as a new one, but they will help wind back the clock and help keep it ticking longer into the future.
If a compression test shows the piston rings are worn (experienced mechanics can also spot other clues) a “short engine” overhaul might cost up to 10 percent of the vehicle’s value, but it will give an old engine a new lease of life.
The principles apply to all turbo diesels and, in diverse ways, to all old cars. BY DAILY NATION