What's That Sound?

By Kristen Castillo

August 11, 2017 4 min read

Cars make lots of sounds -- idling, revving, cruising -- but some noises aren't normal. Take it seriously when you hear unusual sounds like rattling, whistling or knocking.

"Any time you have an out of the ordinary noise, it's important to have it looked at by a qualified technician," says Jill Trotta, the director of the automotive group for RepairPal. "Catching problems early can often save you time and money. Having a vehicle that is safe to operate is important."

Trotta says the most alarming noises are grinding and thumping, both of which are most often related to brakes and suspension. "These are systems on the vehicle that can create unsafe conditions," she says.

According to the team at Trinity Autosport, a full-service German automotive center, "Any sound that doesn't seem normal should be addressed right away because it can cause a bigger problem."

They continue: "For example, the whining noise from the engine bay can be only at cold start" at first, but if that's not addressed, "your pulleys may seize up and break the drive belt. You'll lose power steering and the alternator and you'll be stranded."

Here's a breakdown of common noises and what they could mean for your car:

--Knocking. Hear a knock? That's probably your engine trying to get your attention. You could have bad spark plugs or the gas and air mixture in your vehicle's cylinders isn't burning properly.

--Whistling. Small air leaks in gas engines can cause a whistling noise. "These sounds introduce extra air into the system and can affect the way the vehicle runs," says Trotta.

--Screeching. A screeching sound from the engine bay usually has to do with pulleys, the timing belt and/or power steering fluid.

--Grinding. Trotta says this sound is serious and should be addressed immediately. Grinding typically signals your brakes are in distress. It's commonly caused by very worn brake pads rubbing on the rotors.

--Chirping. Nope, it's not a bird. That chirping sound you hear could be a sign that one of your car's wheel bearings or axle bearing is faulty. On turns, your steering can feel loose. Get it fixed fast.

--Squeaking. Lots of things can cause a vehicle to squeak. "It can be something as minor as a seat spring to something as major as an engine bearing starting to go," says Trotta, explaining that squeaking is commonly a sign that your brake pads are nearing the end of their life or that a belt is getting loose.

--Thumping. A thumping noise can indicate unevenly worn tires or worn suspension components like struts and shocks, ball joints and CV axles when turning, as well as other suspension-related items.

Richard Reina, product training director at CARiD.com, an online aftermarket auto parts retailer, advises drivers to be aware of changes in sounds.

If existing sounds get louder or new ones pop up, pay attention. Ask yourself the following questions:

--Is it a new sound? Did it just start now?

--When do you hear it? How fast are you going when you hear the noise? What else is going on when you hear it -- are you turning the wheel or going straight? Does it happen when you're hitting the brakes, making sharp turns or going over bumps?

--Under what driving conditions do you hear it? In cold or hot weather? Only during the first five minutes? Only after an hour of highway driving? Only when you're driving between 35 to 40 mph?

--Does the vehicle drive differently since the sound started? Do you have less power? Do the breaks feel weak? Does the steering seem loose? Is there a driving maneuver that stops the noise, such as accelerating, turning or braking?

Once you're familiar with when and how these sounds arise, you'll know what to tell the mechanic.

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