Listen Up: It’s time to see the mechanic
Most of us don't even notice harmless noises as we drive, like wind whistling past the mirrors, or tires humming against the asphalt. But some noises aren't so innocent. You should never ignore certain thumping, banging, clicking, and squealing sounds, especially if they intensify while accelerating, braking, or turning sharply. Delay can allow a problem to worsen, which eventually translates into bigger and more expensive repairs. Here are some of the more common noises and their possible causes:
Knocking in engine compartment: Using a lower-grade fuel than recommended will often cause an engine knock. Simply follow the owner's manual requirements regarding oil, gasoline and tire air pressure, and you should be all set.
Loud bang: Also known as a backfire. Sometimes this happens when the air-fuel mixture is too rich, but it can be a sign that the catalytic converter isn't functioning properly. Either way, it’s best to take it in for a repair, especially if it happens more than once.
Low-pitch humming or whirring under car: This could be caused by any number of things. The differential could need lubricant, the transmission may be failing, the u-joints might be worn or a wheel bearing could be shot, especially if the noise changes with acceleration. When this happens it’s best to take it into a mechanic for diagnostics and repair. The sounds under a vehicle tend to reverberate and echo making it hard to determine the source without the proper equipment.
Popping in engine compartment: If you hear any popping, particularly if it’s accompanied by any engine hesitation, you should have your car serviced as soon as possible It could be indicative of an ignition problem, a clogged fuel filter, worn or dirty spark plugs, damaged spark plug wires, or even a compromised catalytic converter.
Rattles from beneath the vehicle: Usually this happens because something is loose. It could be a loose exhaust system or even loose brake pads.
Squealing or chirping on acceleration: This could indicate a belt or belts are loose and slipping. It could also mean the drive pulley for an accessory such as the water pump has become misaligned.
Squealing or scraping when applying brakes: Squealing can have a number of causes, from dirt on the rotors or pads to badly worn pads or shoes. It could also be caused by a wear-indicator on a pad, signaling that it is time for new brake pads.
If the squealing turns into scraping, that usually indicates bare metal rubbing against bare metal- every depression of the brake pedal is damaging at least one of the rotors. No matter the cause, it's a safety issue and requires attention.
Scraping or grinding when applying brakes:
A grinding or squealing noise when slowing down is probably your brakes and will need to be checked. Take it into your local shop for a test drive with a qualified technician. They may be able to give you an estimate or provide further diagnosis.
Engine chugging, racing or shaking: This could be a performance problem, which may mean your car needs a tune-up. Either way, take it into your local shop for a test drive at the next available appointment.