Troubleshooting Strange Sounds Coming from Your Automobile

You probably know how your vehicle sounds when it’s running properly. Listening to your car can help you troubleshoot problems. If you hear a strange sound, pay attention and react accordingly.

  • You hear a high-pitched squeal that stops when you shut off your engine: Readjust or replace the belt. These belts should have about half an inch of play and shouldn’t be frayed, cracked, or glazed on the underside.

  • You hear a continuous high-pitched sound that may continue after the engine’s shut off: Check the radiator pressure cap. The rubber gasket may be worn.

  • Something ticks rhythmically while your engine idles: Shut off the engine, wait ten minutes for the engine to cool and the oil to settle, and then check the oil level. If you have enough oil, have a mechanic check the valve adjustment.

    If you hear a loud tapping or knocking sound in your engine, pull to the side of the road and call for road service. The source may be a loose rocker arm or carbon buildup inside the engine, but if it’s a loose bearing or a faulty piston, it can destroy the engine.

    Mild knocking or “pinging” may be the result of using fuel with the wrong octane rating.

  • You hear the engine running after you turn off the ignition: Your engine is dieseling. This condition only happens to cars with carburetors. It is usually caused by an idle speed that’s set too high or excessive carbon in the combustion chamber.

  • You hear a whistling noise coming from under the hood: Check the hoses for vacuum leaks. If the whistling comes from inside the vehicle, there’s probably a leak in the weatherstripping.

  • The engine idles with an offbeat rhythm: It’s probably misfiring. Turn the engine off and try the following:

    • Check the spark plug cables for breaks or shorts in the wiring.

    • Remove the spark plugs one at a time and check to see if they’re clean and properly gapped. Replace any that are fouled or burned.

    If attending to the spark plugs doesn’t help, have a technician check the ignition system with an electronic engine analyzer.

  • The idling is rough but even: Have a technician check the compression in each cylinder.

  • Your car makes a loud, abnormal sound: A hole in the muffler is probably the cause. Replace it immediately.

  • The horn is stuck: If your horn gets stuck, pull the wires to stop the noise, as shown here.

    If your horn gets stuck, pull a wire to silence it.
    If your horn gets stuck, pull a wire to silence it.
  • You hear a sound but can’t locate the source: Get an old stethoscope. As shown here, take off the rubber disc and insert a piece of tubing in its place (about 1-1/2 inches will do). Then put the plugs in your ears, run the engine, and move the tube end of the stethoscope around the hood area. The stethoscope amplifies the sound as you near the part that’s causing it.

    A piece of tubing and an old stethoscope make an efficient troubleshooting device.
    A piece of tubing and an old stethoscope make an efficient troubleshooting device.
  • You hear whining or humming sounds on curves: Your wheel bearings may be wearing.

  • Your tires make a weird, rhythmic sound as you drive: Check inflation, tire wear, and wheel balancing.

  • You hear squealing when you step on the brake: You’ve probably worn the brake pads down too far. Get them replaced immediately.

    If you have drum brakes, brake linings that are glazed or worn can cause them to squeal as well.

  • You hear rumbling noises coming from under or toward the rear of the vehicle: The trouble could be a defective exhaust pipe, muffler, or catalytic converter; or it could be coming from a worn universal joint or some other part of the drive train. Have a service facility put the car up on a hoist and find the problem.

  • You hear clunking under your vehicle, especially when you go over a bump: Check the shock absorbers and suspension system. If the sound is toward the rear, your tailpipe or muffler may be loose.

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