by Garrett McKinnon
VehicleMD Staff Writer
Originally published in Winter 2009 Issue

Noises. Every car makes them. Most are routine, everyday sounds we’re used to. But some catch our attention, telling us that things may be amiss.

Identifying a noise and describing it to your service technician can be difficult. To identify what component on your car may be making the offending noise, it helps to answer a few questions for yourself first:

• Where is the noise originating? (It can help, especially if the noise only starts up when the car is in motion, to use the ears of a passenger in the back seat to pin down where the sound is coming from.)

• What is the car doing when the noise starts? Is it sitting still? In motion? Turning? Braking? Accelerating? Be as specific as possible.

• When did the noise occur? Is it ongoing or intermittent? Did you hear it when you first started the car, first put it in gear, etc.?

• What was the outside temperature and weather like when you heard the noise? Believe it or not, these factors can play a major role in the occurrence of strange noises.

Once you’ve got the noise pinned down, describing it is your next step, which is where we come in. Following is a list of noises, sorted by location, that can help you describe problems to your automotive technician or mechanic.

Underhood Noises
Squeal — A rubbery squeal, especially one that is intermittent but growing worse over time, usually means a loose or worn serpentine belt, but it could also indicate a problem with a more expensive accessory component like the car’s air conditioning compressor, power steering pump or water pump.

Growl — Also could be a whine that is audible at all times, even at idle. This could mean one of the car’s accessories is failing. A groaning when you turn the car could also mean the power steering pump needs to be checked for proper fluid level or fluid condition.

Clatter — A metallic clatter coming from inside the engine could mean the engine’s valves are loose, or it could indicate a low oil level or the need for an oil change (old oil tends to “foam,” meaning it doesn’t coat the insides of an engine correctly, which could lead to valve “clatter”).

Hiss — Can also be a whistle. Hearing this under the car’s hood usually means a leak in a vacuum hose. Alternatively, a high-pitched whistle coming from the area near the serpentine belt could indicate an alternator that is being stressed.

Bubbling — A bubbling or gurgling sound means air is trapped inside one of the vehicle’s fluids, most commonly the antifreeze/coolant. You may also hear this sound from inside the vehicle, as the same liquid circulates through the car’s heater core to provide heat.

Flapping — This could mean the serpentine belt is coming apart. Have it checked immediately.

Clicking — A clicking sound in the engine could indicate valves that are slightly loose from wear, an issue that, while noisy, is not particularly worrisome or indicative of broader mechanical problems. Many older engines exhibit this noise, which can sometimes be “cured” by installing specially formulated “high-mileage” motor oil or even synthetic motor oil.

Undercar Noises
Clunk — If you hear this when the car shifts gears, it could indicate transmission problems. Alternatively, if you hear a clunk when you put the transmission in gear, it could indicate worn U-joints.

Rattle — A rattling sound coming from beneath the car usually indicates loose exhaust components. It can also indicate a failed catalytic converter.

Whine — A constant whine when the car is in motion could indicate worn gears in the driveline, usually in the differential. It could also mean the differential fluid needs to be replaced.

Ticking — That ticking noise you hear whenever you turn the car off? It’s just the exhaust system cooling off. For once, nothing to worry about!

Tire/Suspension Noises Knocking — This can also be a clicking or groaning. If you hear it from the tires or suspension when you’re at speed (say, above 40 miles per hour), it could mean a worn constant velocity (CV) joint. If you hear it at low speeds, especially when you’re turning, it could mean a wheel bearing about to fail.

Squeak — A squeak coming from the suspension whenever you go over a bump usually means the rubber bushings that dampen vibration in the suspension system are worn. Can also mean the shocks or struts are in need of a closer inspection.

Clicking — If you hear a clicking sound that changes frequencies as you change speeds, chances are you have some foreign object either stuck in a tire or lodged between a wheel and brake or suspension component.

Howling — A tire that “howls” at high speed likely indicates an alignment problem. Alternatively, it could mean a worn shock or strut is allowing the tire to move slightly. Can also be accompanied by a vibration in the steering wheel.

Brake Noises Squeal/Squeak — The most common brake noise (by which we mean noises you only hear when you apply the brakes). Usually this means that a metal wear indicator in the brake pad has been exposed, indicating it is time to have the brakes replaced. Can also mean a brake is hanging, which can be caused by old or worn brake fluid.

Clunk — Usually means that one or more of the brake components is loose. Requires immediate attention.

Grinding — A rough grinding noise indicates metal-to-metal contact, which usually means the brake pad has been worn through. Have your brakes checked immediately.

Today’s automobiles are mechanical marvels that emit all sorts of pleasant sounds (the whir of a finely tuned engine or the rumble of a sports car’s exhaust) and, occasionally, the not-too-pleasant (the ones we’ve catalogued here are the most common but by no means the only troublesome noises you might encounter). By identifying where and what the sounds are, you can have an honest conversation with your technician or mechanic and potentially keep a small problem from turning bigger and more expensive.