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you & your car

I have a puzzle for you. My engine is leaking oil – or at least I think it is the engine, it may be the transmission because there is a little drop on my garage floor, not a puddle, not much actually, but it is noticeable. I have taken it to the dealer and they have tried to find the source – but to no avail. They said they put it on a hoist and spent considerable time – two hours according to the bill, beneath the car looking for it. I realize the leak is slight enough that it is not a concern to anyone but me. Any suggestions? – Graeme

You don't say what the liquid is that is leaking – water, oil, transmission fluid? Each would have a different source.

Put a little bit of the fluid on your fingertip and feel it. Is it slippery? If not, it is probably water sources. If it is slippery, it is either oil or transmission fluid. Try placing a clean sheet of white paper beneath the vehicle before you park so that you can get a better idea of the fluid – if it is clear, it is most likely water; if it has a reddish tinge, it may be transmission fluid; if it has a brownish tinge or darker, it is likely oil.

Once you have determined what the fluid is, you will have narrowed the search.

Assuming the dealer did in fact eliminate the underside of the engine, transmission etc. you can check out the topside. Once the engine has cooled down, use your fingers and even a light-colored glove and feel around the various possible areas. For example, if it appears to be water-based, touch the various places near the radiator, engine and water pump, anywhere hoses connect the three. Follow the same procedure for hydraulic fluids around the steering and brake system. If oil, around the valve covers etc.

Another trick is to use baby powder, flour or a similar white powder.

Shake a little over potential sources, start and run the engine and, where a fluid comes into contact with the powder, you will be able to see it clearly.

Good luck, this is a tough one because of the lack of space in a modern engine compartment.

Black smoke

I have a Volkswagen Jetta diesel with 135,000 kilomertres on it. Love it, but recently have noticed a cloud of black smoke when I pull away from rest or accelerate briskly. The dealer, over the phone, says the injectors, and perhaps the pump, might need to be replaced. I know their labour rates and VW parts costs and am reluctant to go near the place. Any suggestions? – Alex

I'm tempted to suggest you go straight to the dealer. They have the sophisticated equipment and trained personnel to locate and cure your problem while lesser shops might spend a lot of time trying to narrow it down.

I would not think the injectors would need replacement at that relatively low mileage if good-quality fuel has been used. Perhaps someone had access to industrial or farm-use diesel. However, if a tank or two of low-grade, sulphur-laden fuel had been used, that may be the source of the problem.

The smoke you see is the byproduct of incomplete or poor combustion. This produces what are known as particulates or soot. Normally, under proper combustion, very few particulates are produced and those that are, are captured by a filter designed for that purpose. There are many reasons for the excess soot, including dirty or damaged injectors, improper fuel pressure, loss of compression, worn rings and poor-quality fuel. Looks like you will have to do the expensive service.

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