Old or new, it often happens that a car will begin to produce strange sounds that prove difficult to locate and next to impossible to analyze. Many drivers also have gone through the frustrating experience of taking the noise-making vehicle to an auto service center only to have the sound refuse to make itself audible to the technician. If at all possible, then, the driver should make an attempt to locate the part of the vehicle from which the sound emanates before taking it to a service center. Locating the sound also may enable the driver to determine the cause of the noise.
Here are a few troubleshooting pointers on locating and analyzing strange noises an automobile may produce:
A squealing sound occurs while driving around curves in the road: Check the tires for excessive wear on the outside edges; this would indicate a need for re-alignment. Wheel bearings that have begun to wear also can make squealing sounds. If the squealing sound occurs during application of the brakes, it could mean worn brake pads or worn brake linings (if the car has drum brakes); have the brakes checked ASAP.
A squealing sound heard under the hood until you shut off the engine: Check the fan belts for excessive play and/or signs of wear; adjust (to approximately 1/2″ of play) or replace. If the squealing sound continues after shutting off the engine, check the pressure cap on the radiator for need of tightening replacement.
A squealing sound heard when the air conditioning unit has been turned on: Usually indicates slippage of the A/C serpentine belt; the belt needs adjusting or replacing.
Clicking or clacking sounds:
Clicking sounds emanating from the top of the idling engine: The sound likely indicates a hydraulic lifter either out of adjustment or in a worn condition; the engine needs service center care.
Heavy clacking sounds coming from the engine wall(s): A worn piston connecting rod can make this noise; the noise will occur with timed frequency as the crankshaft turns.
Light clicking sound coming from the engine: This can mean the valves need adjusting according to the car manufacturer’s specifications. It also can indicate oil leakage; check the oil level.
Thumping, banging or popping sounds:
Loud clunking sound that occurs when going over speed bumps: The shock absorbers may need replacing or the tailpipe may have come loose. Checking the tailpipe is not too difficult, but wait until it has cooled before touching it. Defective shock absorbers need the attention of a qualified service technician.
Loud or continuous popping sounds: If, during sudden acceleration of the car loud popping sounds (back-fire engine noises), occur suspect the engine has gotten out of time. Check the timing chain or belt for looseness. If subdued popping or “chug-chug-chug” sounds happen after turning the engine off, the car may be dieseling, caused by high levels of carbon in the combustion chamber; this won’t happen in a car that does not have a carburetor, however.
Continuous thumping sounds while driving at various speeds: This kind of sound often originates with the tires, tires that may need reinflating, balancing or replacing; a tire dealership can help here.
If you have difficulty pinpointing the exact location of a noise made by your car, obtain a three- or four-foot length of plastic pipe. Place one end of the pipe against the engine wall or another part of the car and the other end near your ear. The hollow tube should help you isolate the sound. A length of broomstick, though not so reliable as a plastic pipe, also will help in isolating a peculiar noise.