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you & your car

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QUESTION: My daughter moved out west after university and is driving home for a visit this summer. She has a relatively new car, but asks what she should do to ensure a trouble-free drive. What do I tell her?

Terry

ANSWER: I can commiserate, my daughter is moving across the country after her wedding this summer and they will be driving his not-so-new car from coast-to-coast. I'd advise your daughter the same as I did mine - have the vehicle examined stem to stern by a competent and trusted technician.

In your case, the newer vehicle will require a much less stringent check, but the basics are the same - safety is the primary consideration. You can't ensure a trouble-free drive but you can certainly improve the odds with an hour of examination under the hood and on a hoist.

You can complete many of these checks yourself with a friend or family member helping during a 10-minute session in the driveway. Here is my list:

  1. Tires: the single most important item. Check for plenty of tread, even tread wear, proper pressure, no signs of bulges, cracks or aging. Check the spare, too!
  2. Brakes: plenty of life left on pads or linings, not grabbing, no vibration.
  3. Suspension: no free play or signs of leaks around shock absorbers covering CV joints
  4. Lights: check daytime running lights, headlights (high and low beam), turn signals and back-up lights.
  5. Wipers: install new blades if more than a year old.
  6. Leaks: look for any signs of fluid leaks around and under the engine, transmission and differential.
  7. Belts and hoses: look for cracks or soft spots in hoses, shiny or frayed worn spot on belts.
  8. Engine: put through full diagnostic check if a high-mileage or old vehicle.
  9. Fluids: oil, transmission, brake and steering systems, windshield washer, coolant.
  10. Roadside assistance: The gift of a membership will lower dad's stress level.

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OVERHEATING

QUESTION: My GMC Sonoma overheated the other day for seemingly no reason at all. I drove to the city to pick up a new fridge we bought at Sears and on the way back the temperature light came on. The truck has been trouble-free and well maintained. The fridge doesn't weigh that much. What could have gone wrong?

Ross

ANSWER: The problem might not have been weight. It could have been aerodynamic drag - the resistance of air to a body moving through it.

Depending on the shape of the vehicle, as much as 65 per cent of the fuel consumed, or energy produced by the engine, is used merely to overcome air resistance or aerodynamic drag. That tall, square fridge sticking up above the cab required the engine in your truck to work much harder than normal.

Without getting too technical here, when you are driving along at a steady speed the engine has to produce enough power to overcome the aerodynamic drag created by the vehicle pushing through the air. When the force provided to the tires by the engine matches the force of the drag, when the two forces are equal and constant, the vehicle will maintain a steady speed.

As speed increases, the power necessary to overcome the forces of aerodynamic drag increases as a cube of the velocity. In other words, if 20 horsepower is needed at 60 km/h, 160 horsepower would be needed at 120 km/h.

As a kid you probably held your hand out the window and played with how it felt when flat or upright. Try that at 60 km/h and again at 120 km/h and you will see what I mean. Actually, don't try it, you could be seriously hurt!

If you were driving at higher speed, the engine cooling system was probably not able to overcome the heat generated by the engine working so much harder.

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