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Driver's Ed. | DO IT YOURSELF

See No Evil? Hear No Evil? Smell No Evil? Try--You Could Prevent Costly Troubles

October 29, 1998|DEANNA SCLAR

You may know enough to keep your eyes on the road, but are you blind to signs of trouble that can leave you stranded on the freeway? If you use not only your eyes but also your ears and sense of smell, you can prevent minor problems from reaching major proportions.

If you report your sensory clues to your mechanic, you may also save on labor charges by reducing the time he or she would have spent on diagnostic test-drives. Here are some things to look, sniff and listen for, what they may mean and what you can do about them.

Smoke Signals: White vapor on a cold morning is normal. If it continues after the car has warmed up, it could indicate a cracked engine block or leaky head gasket.

Light-gray smoke may mean you're burning transmission fluid. Does the fluid on the transmission dipstick look or smell burned? You may simply need to replace an inexpensive vacuum modulator or have the transmission serviced. Do it before you need major transmission repairs.

Light- or dark-blue smoke is often a sign of burning oil. It may simply have not been changed often enough, or it could be leaking past worn rings into the combustion chambers.

Black smoke may indicate that your fuel-air mixture needs adjusting, especially if carbon blackens your finger when you run it around the inside edge of the tailpipe. (Be sure it's not too hot to touch!)

Your Nose Knows: If you smell oil burning, look around the engine for oil leaks and check your oil and transmission dipsticks to see if you need to add or change the oil or transmission fluid. If those look OK, your engine may be overheating for a variety of reasons. Have a mechanic check it out.

If you smell burning oil or exhaust fumes inside the car, open the windows, drive to the nearest service station and have the mechanic check to see if a faulty exhaust pipe is leaking exhaust gases (and carbon monoxide) through the floorboards and into the passenger compartment. This is toxic stuff, so don't procrastinate about getting it fixed!

If you smell gasoline (and you haven't just filled the car with fuel), drive to the nearest service station to have the fuel system checked for leaks. They may originate under the hood, from fuel lines under the car or from the fuel tank. Again, have this done immediately: Gasoline ignites easily and the fumes are explosive.

The smell of burning rubber from under the hood can mean that a loose hose is melting from contact with a hot engine. If the smell seems to come from under the car, feel your tires to see if one is hot. Driving with the parking brake on, or brakes that are dragging, can really heat up the wheels. Your tires will survive, but your brakes may not.

Listen Up! A sudden rise in the noise level can be the result of a faulty muffler; replace it before you get a ticket.

Rough idling may only require a simple fuel system adjustment, but if your mechanic determines that it's due to low compression, your engine may need to be rebuilt or replaced.

Idling with an offbeat rhythm may simply mean a spark plug is misfiring because a spark plug cable is damaged or disconnected. Check to be sure each is securely attached at both ends and isn't cracked, brittle or frayed. If the cables look all right, ask your mechanic to pinpoint the trouble with an electronic engine analyzer.

To hear if your car is idling evenly, engage the parking brake, turn on the engine, leave the car in park and place a stiff piece of paper against the end of the tailpipe. This will amplify the sound.

Rhythmic ticking when your engine idles may be due to insufficient oil or valves that need adjustment or replacing. You can check the oil dipstick yourself. If it reads "full," have a mechanic check the valves.

Loud knocking under the hood is a good reason to stop immediately and call road service. It may simply be a broken fan belt or a rocker arm that needs adjustment, but if the knocking turns out to be caused by a loose bearing or a damaged piston, the life of your engine may be at stake.

Whistling noises under the hood? Check the air hoses for vacuum leaks. Try feeling around the hoses with the engine running and the parking brake on. Or have your mechanic check things out electronically.

Whistling noises inside the car are usually caused by damaged or worn weatherstripping. Close the windows and aim a hose at each of them. If water gets through, you've found the leak. Try to patch the spot with a piece of adhesive-backed foam weatherstripping before you go to the expense of having the entire gasket replaced.

If your tires squeal on curves, check them for wear, misalignment or low air pressure.

Squealing disc brakes may just be chronically noisy. If disc or drum brakes suddenly start to squeal, the pads may be glazed, greasy or worn. Have them checked immediately to prevent damage to discs or drums, which are expensive to regrind or replace.

If the radiator "sings," the radiator cap probably needs to be replaced. Do it before your car overheats on the highway.

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