What's That Noise? A Mechanic's Guide to Strange Car Sounds

Your car shouldn't sound like it's falling apart.When you hear a new noise — especially one that wasn't there last week — your car is trying to tell you something. Here's a mechanic's translation guide to the most common car sounds and what they actually mean.

Squealing Noises

Squealing When You Start the Car

A high - pitched squeal that happens when you first start the engine and fades after a few seconds is almost always a worn serpentine belt . The belt drives your alternator, power steering pump, AC compressor, and water pump. When the rubber surface wears smooth, it slips on the pulleys and squeals.

Urgency: Medium. A slipping belt isn't dangerous immediately, but if it breaks, you'll lose power steering and your engine will overheat quickly.

Cost: $100–$200 for belt replacement.

Squealing When You Brake

A metallic squeal when you apply the brakes means your brake pads are worn down . Most brake pads have a built-in metal tab called a wear indicator that contacts the rotor when the pad is thin, creating that squeal on purpose — it's designed to warn you.

Urgency: High. You have some miles left, but don't ignore it. If you keep driving until the squeal becomes a grind, you'll damage your rotors and double the repair cost.

Cost: $150–$350 per axle for pad replacement. $300–$600 if rotors also need replacing.

Grinding Noises

Grinding When Braking

If your brakes have gone past squealing and into a harsh grinding sound, the pad friction material is completely worn away and you're now pressing metal backing plate against the rotor. This destroys rotors quickly and significantly increases stopping distance.

Urgency: Urgent — stop driving and get this fixed immediately.

Cost: $300–$700 per axle (pads + rotors). If calipers are damaged: $400–$1,000.

Grinding When Turning

A grinding or clicking noise when you turn — especially at low speeds in tight turns — usually indicates a failing CV joint or CV axle.These joints connect your transmission to your wheels and allow the wheels to turn while receiving power.

Urgency: High. A completely failed CV joint can cause you to lose power to a wheel.

Cost: $200–$500 per axle for CV axle replacement.

Clunking and Knocking

Clunking Over Bumps

A solid clunk when you hit a bump points to worn suspension components — sway bar links, ball joints, strut mounts, or control arm bushings.These rubber - and - metal joints wear out, especially on Connecticut's rough roads.

Urgency: Medium to High, depending on the component. Worn ball joints can be dangerous.

Cost: $100–$500 depending on the component.

Knocking From the Engine

A rhythmic knocking or tapping from the engine could be:

• Low oil pressure: Check your oil level immediately. Running an engine with low oil causes catastrophic damage fast.
• Worn lifters or rocker arms: A ticking that varies with engine speed. Less urgent but should be addressed.
• Engine knock(detonation): A metallic pinging under acceleration. Could indicate wrong fuel grade, carbon buildup, or timing issues.

Urgency: Varies. Low oil = pull over now. Lifter tick = schedule service. True knock = get diagnosed soon.

Humming and Whining

Humming That Changes With Speed

A droning hum that gets louder as you drive faster(and doesn't change when you brake or accelerate) usually means a worn wheel bearing. The sound may change when you turn — louder in one direction, quieter in the other — which helps identify which bearing is failing.

Urgency: High. A completely failed wheel bearing can cause a wheel to lock or separate.

Cost: $300–$600 per wheel, including the hub assembly.

Whining When Turning the Steering Wheel

A whine when you turn the wheel likely points to low power steering fluid or a failing power steering pump.Check the fluid level first — it's usually the cheapest fix.

Urgency: Medium. You won't lose the ability to steer, but it will get harder.

Cost: Fluid top-off: $20–$50. Pump replacement: $250–$500.

Rattling

Rattling Under the Car

A metallic rattle from underneath often means a loose heat shield on the exhaust system. These thin metal shields can corrode and loosen, especially in salt-belt states like Connecticut.

Urgency: Low. Annoying but not dangerous. Some shops will tighten or remove the shield.

Cost: $50–$150 to secure or remove.

Rattling From the Engine Bay

A loud rattle only when the engine is cold could be a timing chain that's stretched. Timing chain replacement is a major repair ($1,000–$3,000) but ignoring it risks catastrophic engine damage if the chain jumps or breaks.

When to Get Noises Checked

Here's a simple rule: if a noise is new, it matters. New sounds mean something changed mechanically. The sooner you identify it, the cheaper the fix usually is.

Hear Something Strange ? Bring It In.

At Strong's Alignment Services, we'll listen to your car, identify the noise, and tell you honestly what it means and what it costs.No guesswork, no pressure.

Call: (860) 569 - 1440 | 195 Silver Lane, East Hartford, CT