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A moving car is a complex symphony of sound, most of it reassuring — tires humming, engine rumbling, tailpipes roaring. But every now and then a dissonant note creeps into the mix — and the alert driver's ears prick up: Did you hear that?
Here's a guide that identifies those oddball sounds and helps you sort out which conditions you can let slide and which ones mean repairs — and how fast you need to make them.
HUMPTHUMP THUMPTHUMP THUMPTHUMP
Where: From one or more tires.
When: At low speeds, especially in the morning. Speeds up with car.
What: Flat-spotted tire. As the tire rotates the flat spot thumps on the ground. Nylon-cord tires will flat-spot overnight and make this sound until they warm up. It's usually worse in colder weather. You can permanently flat-spot the tires by locking up the wheels, grinding massive amounts of rubber off the tread in one spot.
Urgency: Nada.
Fix: Replace your nylon tires with steel-belted tires. If you've ground down your tires like a pencil eraser, you can either live with the vibration until wear reduces the flat-spotting, or buy new tires.
FFFFffff ttttFFFF ffff ttttFFFFffff tttt
Where: Under the hood.
When: Most noticeable at idle.
What: An exhaust manifold gasket has failed, venting hot exhaust gases to the air.
Urgency: It's not getting better on its own. The blowtorch of corrosive gases will eventually damage the manifold. Oh, by the way: Carbon monoxide from the leak may make you drowsy or dead.
Fix: Replace the exhaust manifold gasket before the leak eats a hole in the manifold.
Ticktickticktick
Where: Under the center of the car, toward the rear.
When: While in motion and varying with road speed.
What: U-joint (rwd or 4wd only). A U-joint in your drive shaft has finally run out of grease, is getting loose, and is about to fail.
Urgency: That's really just an urban legend about cars pole-vaulting over broken driveshafts when U-joints fail at speed, right?
Fix: Replace all the U-joints and keep the new ones greased regularly.
EEEEEEEeeeee
Where: Inside the wheels.
When: Slowing down; it's sometimes worse on damp days.
What: Your brake pads are stroking the discs like a violin bow.
Urgency: Sometimes they do that. Your brakes still work fine.
Fix: Try new pads, adhesive to hold pads to the piston, or shims to insulate the piston from the pads. Another option: earplugs. (Sometimes the sound is difficult to eliminate.)
SSSSSSSSSSSS
Where: Under the hood.
When: Anytime the engine is running, but it's most noticeable at idle speed.
What: Vacuum leak. A rubber or plastic vacuum line or fitting has split or fallen apart.
Urgency: If you're wondering why your Check Engine light is on and why your car idles poorly, this is probably why.
Fix: Reconnect or replace the line.
Clang
Where: Under the center of the car or truck, near the middle.
When: Starting off at traffic lights. Most often heard on pickups with automatic transmissions, not manuals.
What: The splines that allow the driveshaft to change length where it connects to the tailshaft are binding as you slow down and then releasing when you start off.
Urgency: Annoying, but They All Do That — or at least some of them do it some of the time.
Fix: Packing the spline area with special grease helps for a month or so. Or just sell the car or truck.
ThunkThunkThunk
Where: One or both front corners of the vehicle.
When: Going around slow, sharp corners under light throttle.
What: A CV joint that allows your front wheels to turn and still be powered is loose. The boot has failed and let out all the CV joint's grease, or maybe it's just time for it to wear out.
Urgency: Don't leave town. Don't use a lot of throttle around sharp turns. Your car will stop suddenly when the joint completely fails.
Fix: Replace the entire off ending half-axle.