Engine Noises and What They Mean: 5 Common Sounds, Causes & Fixes

What should I do when my engine makes a strange noise?

Stop and check the oil level. Low oil is the most common cause of ticking and can lead to serious damage. If you hear a deep, heavy knock, a loud grinding, or the red oil-pressure light is on, shut the engine off safely and arrange a tow instead of driving on.

Squealing, light ticking that disappears after a top-up, and hissing without overheating are less urgent, but have them inspected soon.

Engine noise cheat sheet: causes and urgency

General guidance only. A noise can have several causes, so a technician should confirm the diagnosis.

1. Engine knocking: rod knock vs pinging

Rod knock is a deep, heavy knock from low in the engine that follows RPM and gets louder under load. It usually comes from a worn connecting-rod bearing, often after low oil level or low oil pressure. It does not go away with an additive or adjustment, and driving on can destroy the engine, so stop and arrange a tow.

Pinging (detonation) is a lighter metallic rattle under acceleration. Common causes are low-octane fuel, carbon build-up and ignition timing problems. Use the fuel grade in your owner’s manual and have the engine scanned if it continues.

2. Engine ticking or tapping

A light tick from the valve cover area is often low oil or low oil pressure starving the hydraulic lifters. Other causes include a worn lifter or rocker, an exhaust manifold leak (the tick may fade as the metal heats and seals) and, on direct-injection engines, normal injector clicking.

• Check the oil level now. If it is low, top it up and see if the noise stops.
• If it stays after a correct fill, have it diagnosed before a long trip.
• A tick that is loudest right after a cold start and fades within about 30 seconds is often a lash adjuster, so check the oil level and your oil-change interval first.
• If the red oil light comes on, or the ticking turns into knocking, shut the engine off.

Use the viscosity in your owner’s manual, and see how to fix low engine oil pressure and how to tell if your engine is damaged from no oil.

3. Squealing or chirping

A squeal at start-up or when turning usually points to a worn serpentine belt, a weak tensioner or a failing pulley or accessory. A failed belt can mean losing power steering and battery charging, so inspect it soon. Accessories such as the alternator, water pump or power steering pump can also make noises that sound like they come from inside the engine.

4. Grinding

Grinding while running can mean a failing bearing, pulley, alternator or other part, or a lubrication problem. A grinding that happens only when starting points to the starter or flywheel. If a grind is loud or constant, avoid driving and have it checked, because it often means metal-on-metal contact.

5. Hissing or whistling

A steady hiss like escaping air can be a vacuum leak. A hiss after shutdown may be hot pressurized coolant escaping, which is more urgent. Steam, a sweet smell or a rising temperature gauge means stop and let the engine cool before opening anything. An exhaust leak can also hiss or tick near the manifold.

What to check first, and when to stop driving

1. Park safely and check the oil level and color with the engine off on level ground. Our guide on how to check engine oil shows how.
2. Look at the dashboard. The red oil light or temperature warning means stop. See what dashboard warning lights mean.
3. Notice when it happens: cold start only, idle, under load, or turning.
4. Listen for the source. Top-end ticks come from near the valve cover, and deep knocks from low in the engine. Be careful around moving belts and fans.
5. Stop driving for a deep knock, loud grinding, red oil light or overheating. Otherwise book an inspection soon.

Diesels often have normal cold-start clatter that eases as they warm up. If the noise is new, louder or comes with power loss, get it checked.

Engine noise FAQ