NOISE PROBLEMS

Is Your CAR Trying to Tell You Something?

Troubleshooting those weird noises coming from your car can help you determine needed repairs. It's important that you listen to what your car is trying to tell you.

The best method these days is a stethoscope. Indispensable in finding the source of a sound, it's also a lot easier to place it where you want it.


Here are a few general guidelines to what your car's noises might mean:

BANG
A sharp, startling sound, like a rifle shot, means you're dealing with the dreaded backfire. You'll probably be able to trace this to something that's causing a rich air/fuel mixture.

BOOM
A hollow, low-frequency sound/sensation, this makes you feel as if you're riding inside a metal drum and the atmospheric pressure is rapidly changing between positive and negative.

BUZZ
An annoying "bzzzzzzzzz" sound, like a trapped insect, can usually be traced to unfortunate positioning of interior trim parts. Have somebody else drive while you press, pry and pound on every likely spot.

CHIRP
This sounds like birds are nesting under your hood. You can probably blame a maladjusted or misaligned belt, but don't ignore the idler pulley. Or, it could just be your tires when you hit second gear.

CLANG or CLANK
This sound couldn't possibly be emitted by any light, flimsy parts. It's coming from a heavy, essential component, such as a set of gears. A good example is the sound a bad rear axle pinion bearing makes when you drop the transmission into Drive, then Reverse.

CLICK or CLACK
It's typically repeated rhythmically. With OHV, perhaps a stuck lifter is allowing clearance in the pushrod/rocker valve, or maybe a solid lifter is just out of adjustment. When emanating from the nether regions of the front end during a turn, this sound may be traced to an outboard CV joint.

CLUNK
A heavy bumping sound, softer than a clang, usually indicates you should look at suspension bushings, including shock or strut mounts.

FLAPPING
Maybe a belt's coming apart. Fan interference is another possibility.

GRINDING
A horrible, torturous sound, means something's going awry - and fast. If it occurs when the brakes are applied, the linings are gone.

GROAN
Something's dry, probably a suspension component. If it's metal, it's going to break really soon.

GRUNT
Again, a dry joint somewhere in the underpinnings is likely. If it's in the stoppers, suspect rear drum shoes contaminated with brake fluid or gear lube from a defunct axle seal.

HISS
If it's continuous and changes with rpms, it may be normal belt noise. Otherwise, a slow leak in the cooling system is likely.

HUM
We don't mean what the radio does between stations, but the noise a differential or wheel bearing makes. If it responds to acceleration/deceleration, suspect the differential. Then look into the bearings.

KNOCK
Like knuckles on a wooden door, this sound is deep and hollow. Often it's a warning that something important (and expensive) is about to let go.

PING
Sort of like little ball bearings being poured on a tin roof, this sound is detonation (aka spark knock) - a phenomenon in which the air/fuel charge explodes violently instead of burning smoothly.

POP
This sounds like a shotgun being fired through a mattress. It usually means the engine's coughing back through the intake.

RATTLE
They didn't coin the term "rattle trap" for nothing, you know. People have been fighting this annoying noise since the automobile was invented. Thanks to plastics, better rubbers and more highly engineered fasteners, rattles are less prevalent than they once were. But you'll still get them, usually in the undercarriage somewhere. Likely culprits include exhaust system parts, calipers or loose brake pads.

ROAR
If it's not something obvious like a blown exhaust system, maybe the transmission is never shifting into high or overdrive.

RUMBLE
While a pleasant enough throaty sound when it's from a free-flowing exhaust system, it can easily cross over into the unacceptable sound range. But don't choke the power down with an overly restrictive cheap muffler. For tire and road noise, see "ROAR".

SCRAPING
Something like "jeet-jeet-jeet-jeet" that speeds up as the car gathers speed probably means an object of one sort or another is contacting the driveshaft, possibly an exhaust shield or hanger or the parking brake cable. Your brake system, especially drum hardware, is also a distinct possibility.

SCREECH
"SQUEAL" taken to the max. See "SQUEAL".

SIZZLING
Like the sound of bacon frying, this is usually only with the engine off. Oil may be leaking onto the exhaust manifold or a minor coolant seepage may be occurring.

SQUEAL
This sound is usually related to brakes and belts. On the former, maybe you're down to the pad wear indicators. Or the discs and semi-metallic linings aren't getting along due to poor rotor finishing or washing, an assembly error, a troublesome friction formula or the like. Squealing is certainly common in disc brakes, but clunking can also occur on initial application if the shoes are loosely mounted.

TAP
Much the same as a click, sort of like beating on the intake manifold with a screwdriver blade, this is usually valvetrain-related. Think about stuck lifters or an adjustment that provides too much lash.

WHINE
This is a hard one to pin down, but it's apt to come from worn ball or roller bearings, mismatched gears, too light a lube in a manual gearbox (ATF, maybe?) or alternator bushings getting ready to go.

WHIR
The sound made by happy mechanicals. It's one of the few noises you probably shouldn't worry about.

WHISTLE
Usually occurring at higher speeds, it's probably wind noise. But do double check if the latches and tumblehome are properly adjusted. Are the body gaskets in good shape?

REMINDER: Please seek the assistance of a professional car mechanic.


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