Is My Car Dying?
January 18, 2007 1:01 PM   Subscribe

Car makes an Odd Sound

I have a 2001 Hyundai Santa Fe . When driving down a quite street i can hear the car make a fluttering almost light clicking sound from underneath. It only makes this sound while I have my foot on the gas. If I back off the Gas the fluttering from underneath goes away. Its a faint sound and I dont notice any problems otherwise with the car. What could this be? Ive checked to make sure nothing is loose or ratteling. It almost sounds like a playing card in bicycle spokes but faint. Should I be concerned? Transmition? Cadalytic Converter?
posted by slowtree to Travel & Transportation (12 answers total) 1 user marked this as a favorite
Sounds to me like a slight exhaust leak. Does it grow louder/faster with increased throttle/revs?
posted by TheNewWazoo at 1:04 PM on January 18, 2007

Try the CV shaft on that side. Check for a cracked boot. When the boot gets cracked/broken, it allows the lubrication to exit and the constant velocity shaft starts to gring against the knuckle. It should also make a clicking sound (a bit louder) when you turn the wheel from a dead stop and press the accelerator. Like when going around corners. I hope this helps. A sure fire way to tell if the CV shaft is responsible. I'll be the noise quiets down when it's raining. The water is probably acting as a lube of sort, reducing the friction of the CV joint. Although the silence is very, very temporary. Good luck!
posted by winks007 at 1:09 PM on January 18, 2007

Response by poster: The sound does get more rapid the faster/ more revs i go but not louder (that i can tell). You almost wouldnt here it if it wasnt for being quite or an echo off a wall. I'm sure its not the CV joint I have dealt with those in the past and im blessed that this isnt the issue. Exahst leak
posted by slowtree at 1:36 PM on January 18, 2007

A ticking sound can mean a number of things. One of the more common things is needing to have your valves adjusted. I'd probably take it in and have a mechanic check it out though.

To me, it very much doesn't sound like an exhaust leak (loud droning) or a CV-joint (only makes the thumping sound when you are turning).
posted by knave at 1:37 PM on January 18, 2007

Apart from what has been said, could also very well be the engine's valves or valve timing belt (if it has a tb). Bad timing or valves make a ticking sound.
Open the hood as it's idling and check if you can hear the sound.
Having a partner rev it will tell you if it's indeed in the engine.

If it only makes the sound while driving, it's suspension parts.

Oops. On preview, knave gets the nod.
posted by artdrectr at 1:46 PM on January 18, 2007

Can you hear it by applying gas while sitting still in neutral? If not, valves or exhaust leak are far less likely, since those would rarely be altered by engine loading.

If it happens at relatively low RPMs and you have an auto transmission, it won't hurt to try it sitting still with a little load by holding the brakes on and giving a bit of gas in drive. (Not for too long though!)

Someone standing outside might be able to hear it better, too.

Knowing if it is dependent on movement will narrow things significantly either way.
posted by SpookyFish at 2:01 PM on January 18, 2007

You're sure it's not a heat shield above your muffler/catalytic converter?
posted by M.C. Lo-Carb! at 2:02 PM on January 18, 2007

Response by poster: It doesnt sound like a ticking (valves, the sound a car makes when low on oil) more like a fluttering. I do not hear the sound when the car is in neutral. I only hear it while im on the trottle driving. If a take my foot off the gas and coast it either goes away or becomes quite enought that i cant hear it anymore. Ill try putting the brakes on and reving it a little to see if i can hear it.
posted by slowtree at 2:06 PM on January 18, 2007

While it's parked and running, have somebody else push the gas a little while you listen to try to figure out where it is.
posted by koeselitz at 3:23 PM on January 18, 2007

On preview: forget it, sorry.
posted by koeselitz at 3:24 PM on January 18, 2007

Exhaust leaks are easy enough to find with a stethescope, and most muffler shops will be able to check the exhaust system from header to tailpipe in about 10 minutes, for free. Small cracks in the exhaust mainfold, or leaks in the gasket between the manifold and the head will sometime sound like funny little ticking noises, of lower than engine frequency, as the leak is only "puffed" when the adjacent cylinder is dumping exhaust gas into the manifold. It's a noise that is more prominent with throttle, than when the throttle is closed, but it will also be readily apparent whether the car is rolling or not, and it will change predictably with engine speed.

A CV joint noise is usually more of a sharp clicking sound, that will change with the angle of the wheel, and the incipient drive stress being transmitted. Turn the wheel sharply while accelerating usually causes the noise to become much louder, while straightening the wheel and backing off the throttle can cause it to disappear entirely.

You could also have a brake disc that is "warped" or has picked up a bit of road trash, and is rubbing your caliper. Or, you could have a tire with a broken steel belt, which I've heard make the kind of "fluffing" noise you describe. These noises will change directly and only with wheel speed, regardless of what the engine speed is doing. If you put the car in first or second gear, get it up to 20 or 30 miles an hour, and the frequency and pitch of the noise remains what you've been hearing, the cause is wheel or brake related, as the engine is turning over much, much faster in lower gears.
posted by paulsc at 3:58 PM on January 18, 2007

A worn speedometer cable can cause a faint clicking noise only under acceleration. The sound seems to come from behind the steering wheel.
posted by na2rboy at 6:41 AM on January 19, 2007

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