6 strange car sounds you shouldn’t ignore

Illustration by Rui Ricardo
Date:3 July 2014 Tags:

Don’t just turn up the radio to drown out the noise. Here are six strange car sounds that demand prompt attention. By Murilee Martin

1. A diesel-like clattering in your petrol-powered car.

Worst-case scenario: Detonation, also known as pinging or knock.

Bad stuff that can happen: Damage to spark plug electrode, pistons/piston rings, and/or knock sensor.

Why: Things such as contaminated petrol or incorrect ignition timing cause the fuel to go boom too early. If left unchecked, you risk serious engine damage.

What to do: Switch to higher-octane fuel, which resists detonation, and check the timing.

2. Questlove drumming underneath your rear-drive car when it’s moving, increasing with vehicle (not engine) speed.

Worst-case scenario: Failing universal joint or driveshaft bushing. Bad stuff that can happen: U-joint fails completely, driveshaft digs into pavement, and the car pole-vaults and crashes.

Why: Both the U-joint and bushings simply wear out. The noise comes from the driveshaft flopping around like an ailing fish.

What to do: Inspect the driveshaft for worn or broken parts, replace them, or get to a mechanic.

3. A million fingernails scraping on a chalkboard when you start up the engine or accelerate from a stop, often during winter.

Worst-case scenario: Loose accessory drive belt.

Bad stuff that can happen: Your enraged neighbours will kill you.

Why: The belt is slipping on the pulleys, either due to age and wear, or improper tension.

What to do: Inspect the belt for minor cracks or fraying. Replace as needed.

4. Sharp tapping like a clunky washing machine, increasing with engine revs.

Worst-case scenario: Connecting-rod knock.

Bad stuff that can happen: Broken rod blasts hole through the engine block; metal parts and flaming oil shoot out.

Why: Usually a failure of a rod bearing due to oil starvation.

What to do: Stop driving immediately. If caught early, the bearing can be replaced.

5. Grinding metal – think train going around a bend or braking to slow down as it pulls into a station.

Worst-case scenario: Brake pad or shoe material completely gone.

Bad stuff that can happen: Destroyed brake rotors or drums. Car may pull to one side under braking and possibly crash.

Why: Brake pads should make a squeal when the pad has worn down to the danger zone. But sometimes we don’t notice this sound.

What to do: Fix the brakes.

6. A whine like an empty ice machine when you turn the steering wheel, especially at low speed.

Worst case scenario: Falling power-steering pump.

Bad stuff that can happen: Loss of steering assistance.

Why: Low power-steering fluid or a pump groaning to death.

What to do: Check the fluid level, top off as needed, and get ready to buy a new pump.