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What's That Noise? 10 Ways to Identify Car Issues By the Sounds It Makes

That 1989 Corolla of yours makes all sorts of noises Toyota hoped it never would, most of which are as harmless as they are annoying, yet some of which can be as detrimental as they are deafening. The trick is knowing which sounds you can brush off as innocuous racket—like that rickety glove-box door you duct-taped back into place—and which you ought to take care of with a quickness.                                                     

Belt on an engine

Whines and Squeals From Under the Hood

You notice it mostly when turning the ignition over, but let it go on long enough and that shrieking sound’ll greet you anytime your engine’s running. Most of the time this forewarns an accessory belt that’s about to fail or a new one that’s been muscled far too tight. Inspect whatever belts are wrapped around things like your A/C compressor, power steering pump, alternator or water pump for excessive wear and for too much or too little tension.

Belt with grooves on an engine

Humming From Inside the Engine

Tension up that timing belt too much and, unlike an overtightened accessory belt, you can cause all sorts of expensive damage inside that big box of pistons and valves. A droning sort of humming sound emanating from underneath the cylinder head cover(s) is a good sign that the same guy who overtightened your alternator belt installed that timing belt. In most cases, it’s easiest to release and reset the timing belt’s tensioner instead of trying to figure out whether or not the right amount of tension’s been applied.

A hand fiddling with a part on an engine

Clicking or Tapping From Inside the Engine

The sound of loose change rattling around underneath your engine’s cylinder head cover(s) is most likely a result of not enough engine oil or a whole lot of loose valves. All of this won’t annihilate everything else inside of that cylinder head(s) of yours but loose valves can lead to a loss in power and premature wear. Be sure it’s the valves and nothing more serious by revving up the engine and paying close attention. Does its tempo pick up and hold some sort of rhythm? It should. Clicking variations can also point to a small exhaust leak, or even detonation.

Inside of an engine block

Knocking From Inside the Engine

This is one of the last sounds you want to hear and about the easiest to diagnose. Clacking sounds emanating from the lower half of an engine often mean a rod bearing or the rod itself is in trouble, typically due to oil starvation or over-revving. Rev the engine and listen up. Does the knock continue and get faster as the engine spins higher? Sucks for you. Don’t confuse all of this with the sound of a bent or burned exhaust valve, a loose timing chain or a cracked flex plate, though, which can also make all sorts of ugly noises but won’t be as rhythmic as that bad rod bearing. Disable spark to the suspected cylinder, listen for the noise to quiet down some and know for sure that you’ve got a bottom end to take apart.

Brake pad on its mounting

Squealing or Scraping From Behind the Wheels

There aren’t a whole lot of rotating parts behind your wheels, which can make diagnosing these sort of sounds easy. High-pitched squealing or scraping sounds that get worse when you stomp on the brake pedal are a sign of worn-out pads or shoes and, if you let it go on long enough, bungled-up rotors or drums. Often times, it’s the pads’ wear indicators making all of this noise, which are there to get you to go out and replace them as quickly as possible. Let it go on long enough, though, and that noise will be because of all sorts of other expensive reasons.

Axle connected to the wheel

Clunks From Underneath: Part One

You hear a clunking sound, only this time you know it’s not coming from the engine. It’s coming from underneath, it’s more obvious when you speed up and it gets louder when you turn. We’re talking about a torn CV (constant velocity) joint boot that’s lost most of its packing grease and has now got all kinds of metal pieces rubbing up against one another. Put it off long enough and you’ll need a tow truck and a whole new halfshaft to fix all of this.

Coil spring in the suspension of a car

Clunks From Underneath: Part Two

Most any other clunk, knock or rattle coming from underneath your car will have something to do with an engine or transmission mount or the suspension. Blame the shocks or struts for clunks that occur when going over bumps, dips or around corners. Blame an engine or transmission mount for ugly noises that take place when you mash on the accelerator or stomp on the brakes.

Hands holding a car part

Rattling That Starts When Stepping On the Clutch

Step on your clutch pedal and your transmission’s throwout bearing gets shoved against its pressure plate and starts spinning around. If it’s worn out or wasn’t lubricated properly when installed, this is about the only time it’ll make noise. Let off the pedal, be sure that whirling sort of rattling sound is gone and know that a new throwout bearing is in your immediate future.

Gears of a clutch with the cover taken off

Rattling That Stops When Stepping On the Clutch

Let off your clutch pedal and listen to that rattling sound coming from what you think is your engine. Step on the clutch pedal to confirm it’s gone away. You’ve just diagnosed a bad transmission input shaft bearing, in, which case, it’s okay to shed a tear or two.

Clutch on a table with the case taken off

Crunching When Changing Gears

Whether or not you need a whole new gearbox is between you and your transmission guy, but crunching sounds when rowing through the gears will never be a good thing, nor an inexpensive one. Experience it with a single gear and you can bet it’s the transmission’s synchros, which, most of the time, can be purchased separately. You’ll still have to pay your transmission guy to pull the whole thing apart, though. Experience it through every gear and, more than likely, you’ve got yourself a worn-out clutch.

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