Car noises and what they mean
By LSG Auto Nation · · Updated
Short answer
Most car noises point to one part of the car. Squealing or grinding when you brake usually means the brakes. Clunking over bumps usually means the suspension. A roar that gets louder as you speed up is often the exhaust. Clicking when you try to start is usually the battery. Grinding brakes need checking right away.
Cars rarely break down without warning, and the warning is often a new noise. When you hear it, where it comes from and whether it changes with speed all help a mechanic find the problem quickly.
Common car noises at a glance
| Noise | When you hear it | Usual cause | How soon to act |
|---|---|---|---|
| High-pitched squeal | When you brake | Brake pads are almost worn out | Soon |
| Grinding or scraping | When you brake | Pads worn through, metal rubbing on metal | Right away |
| Clunk or knock | Over bumps | Worn suspension parts | Soon |
| Rattle from under the car | Sitting still or over bumps | A loose metal shield or exhaust hanger | Soon |
| Roar that gets louder as you speed up | When you speed up | A leak in the exhaust pipe or muffler | Soon (fumes can get inside) |
| Hum that gets louder with speed | On the highway | Uneven tire wear or a worn wheel bearing | Soon |
| Clicking when you try to start | When starting | A weak battery or a starter problem | Before you get stuck |
| Ticking from the engine | While the engine runs | Low oil, or worn engine parts | Check the oil today |
| Squeal from under the hood | Starting up or speeding up | A worn or loose belt | Soon |
| Hissing under the hood | After driving | A coolant leak | Soon (the engine can overheat) |
Brake noises
A squeal when you brake is often on purpose. Many brake pads have a small metal tab that squeals when the pads get thin, to tell you they’re due. Grinding means that warning has passed, and metal is now rubbing on metal. Read more about brake warning signs, or see brake pad replacement.
Clunks over bumps
Clunks and knocks over bumps usually come from worn suspension parts, the parts that let your wheels move up and down. Common culprits are the sway bar links, ball joints and bushings. A badly worn ball joint can break, so get any new clunk from the front of the car checked soon.
Rattles and roars from underneath
A rattle under the car is often a loose heat shield, a thin metal cover over the exhaust, or a broken exhaust hanger. A roar that gets louder as you speed up usually means an exhaust leak. Exhaust fumes can get inside the car, so don’t put it off.
Engine and starting noises
Clicking when you try to start usually means a weak battery or a starter problem. See car won’t start. Ticking from the engine can mean the oil is low, so check the dipstick first. If the oil is fine and the ticking doesn’t stop, have the engine checked.
How to describe a noise to your mechanic
The more you can tell us, the faster we can find it:
- When: braking, speeding up, turning, going over bumps, sitting still, or only when the engine is cold?
- Where: front or back, left or right, under the hood or under the car?
- What changes it: going faster, revving the engine or turning the steering wheel?
- Since when: did it start suddenly, for example after you hit a pothole?
A short video on your phone that captures the sound helps a lot.