What's this weird rattling sound?
December 25, 2010 9:24 PM   Subscribe

AutoFilter: My '06 Corolla is making these weird rattling/grinding noises (recorded today for your listening pleasure). Muffler problem, maybe?

This problem started within the past month or so, when it got cold enough to snow.

On good days, the rattling will go away after letting the car warm up for about five minutes or so and driving normally. Other days, the car will persistently make those loud, creaky groans the whole 10-15 minutes it takes me to drive home.

The car doesn't handle any differently, vibrate, or otherwise seem affected when it rattles.

What do you think, MeFites? Is this just a regular car-being-cold thing that I'm unused to, a muffler problem, or perhaps something more insidious...?

Thanks for your input/expertise!
posted by AAAAAThatsFiveAs to Travel & Transportation (17 answers total)
Oh--I forgot to add that it's much louder on the passenger side than the driver's side!
posted by AAAAAThatsFiveAs at 9:25 PM on December 25, 2010

A little hard to hear, but it could be the heat shield - does it sounds like it's coming from underneath the car? I know nothing about cars, but I've experienced some rattling that ended up being the heat shield.
posted by backwards guitar at 9:45 PM on December 25, 2010

Agreed- hard to hear. Was it taken from inside the car? That will muffle the real sound.

A heat shield is a thin, tinny kind of sound usually. Does the noise happen when you are moving, or when it is idling too?
posted by gjc at 10:15 PM on December 25, 2010

CV joints make noise when they go bad. Holes in the muffler make noises. Missing or broken heat shields will sound like a normal car only louder. Could be breaks, tires, power steering, or any other number of things.If this was a guess the correct answer and win money game: I would guess CV joint. I would also say that with the information you have provided there is no way to diagnose your problem. Unfortunately Mefi makes a poor mechanic.
posted by Felex at 11:20 PM on December 25, 2010

For a few bucks, you can buy a mechanic's stethoscope, which is pretty handy for localizing weird under-the-hood noises. The recording you've provided sounds a little like it might be a leaking exhaust manifold or manifold gasket, but that's as much due to what I perceive as an intermittent "spitting" sound in your recording, and the fact that you say the noise sometimes goes away once the car is warm, than it is to any certainty I can have of the cause. With a stethoscope, you just slowly move the probe around, from one end of the exhaust manifold to the other, and if you do have a leak, you'll pin point it easily as a locally loud, intermittment "pfft, pfft, pfft" kind of sound, that increases quickly in occurrence if you rev the engine just a bit.

You can also use the stethoscope to follow your exhaust system all the way to the tail pipe, listening for leaks, if you can get the car up enough to get at it.
posted by paulsc at 12:09 AM on December 26, 2010

The noise alone is not much to work with. Is it triggered or made worse by particular driving events, like turning or braking or accelerating? Does it happen even whenever the motor is running, even when the car is standing still?
posted by jon1270 at 1:42 AM on December 26, 2010

It'd be easier if we had some context to the recording - was it idling, or under load? Where was the microphone (i.e. inside the car or under the chassis)? More frequent when accelerating? What's your fuel economy been like? Without this info I'd guess a faulty CV. With a muffler you'd likely also see a drop in fuel economy as the computer tries to compensate.

Better take it somewhere.
posted by Sutekh at 4:03 AM on December 26, 2010

Have you tried turning off the heater fan?

If it makes the noises as soon as you start up, even before you drive away, it's something on the engine or transmission, since those are the only things that are moving when the car is still. Open the hood and try to locate the source. Could be a bad power steering pump, or a piece of sheet metal on same - my wife's old Camry has one of those that makes a similar noise. Maybe a bad water pump, or something rubbing the fan belts.

If it only makes the noises when the car is moving, my guess is that something is rubbing on a wheel, tire, or brake disk. That could be a piece of the car that's come loose, or a branch or something else you ran over that got caught under the car.

It does not sound to me like any kind of exhaust leak.
posted by Kirth Gerson at 4:45 AM on December 26, 2010

How could it be the CV joint since in the video the car is standing still ? On this car aren't the CV's between the transmission and front wheels?

So, unless I've misunderstood something, maybe you can rule out the CV's.

If it's the exhaust you can usually tell by having someone else in the drivers seat to rev the engine a bit while you listen with head down near the pavement (at the side of the car, not the front or back of course!). Also, with the engine off, try tapping the exhaust components with a hammer or screw driver to hear if anything sounds loose.
posted by Kevin S at 5:14 AM on December 26, 2010

Kevin S is right - it could be that the exhaust system or some part of it is loose and rattling against another part of the car. It could do that without leaking, and with or without the car moving.

I assumed the picture of the car was not connected to the audio.
posted by Kirth Gerson at 6:04 AM on December 26, 2010

Kevin S.- That is just a picture of a Corolla, not his car.
posted by gjc at 8:02 AM on December 26, 2010

Try to take a video, a walkaround with the car idling, and an action segment while driving.

It sounds to me like it could be a heat shield on the exhaust the cat coming apart inside, a broken exhaust mount, or a belt tensioner or idler.

I was a pro mechanic for 10 yrs but I need context/more info.
posted by KenManiac at 9:52 AM on December 26, 2010

Sorry for being dumb.

Of course it's just a random pict.
posted by Kevin S at 12:29 PM on December 26, 2010

'06 Toyota? I'd rule out exhaust unless you've run over a reindeer or something.

CV joints sound unlikely as do heat shields.

IIRC the passenger side of your car is the side where the engine has all of its accessory drives and belts. I'm guessing you've picked up some debris and it's bouncing around in that little loop of belts and pulleys and can't escape.

Just open the hood and inspect. If you don't see anything obvious, check all of the belts and pulleys. It sounds to me like something is amiss there like a loose pulley or a failing bearing on an something belt driven.

Good luck and please let us know what you find!
posted by snsranch at 2:53 PM on December 26, 2010

Thank you for all the great responses so far! Apologies if the recording was fuzzy....

I've been traveling all day, but tomorrow I'm going to make some careful observations about what happens when I accelerate/turn/leave the heat on/idle/etc.
posted by AAAAAThatsFiveAs at 3:30 PM on December 26, 2010

@KenManiac: I'll take a vid tomorrow!
posted by AAAAAThatsFiveAs at 3:33 PM on December 26, 2010


When I was test driving this morning, I figured I'd just go to the dealer :)

You called it, MeFi: Mechanic said that the exhaust system came loose from a hanger and was knocking around... super easy fix, no charge.

Thanks for your input--reassuring AND correct!
posted by AAAAAThatsFiveAs at 9:00 AM on December 27, 2010

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