Timing Belts 101

March 20, 2025

5 min read

March 20, 2025

5 min read

Inside your engine, two shafts spin at different speeds. The crankshaft moves the pistons, and the camshafts move the valvetrain to open and close the valves.

The camshafts spin at half the speed of the crankshaft. This operation is managed by the crank and cam gears, connected by a timing belt or a timing chain. You see timing chains mostly on luxury and vintage cars. This guide focuses on engines with timing belts.

What Is a Timing Belt?

A front view of a V-8 engine that’s been removed from the vehicle, sans timing belt covers. — This is the typical routing of a timing belt on a V-8 engine.

A timing belt is made of synthetic rubber and uses cog-style teeth to mesh with the cogged gears on the engine. They wear out and must be changed at regular intervals, typically between 60,000 and 100,000 miles.

Follow with the manufacturer-recommended replacement interval. These intervals are conservative, but it’s not worth trying to get an extra 10,000 miles out of a timing belt. Sure, it might last longer. But if it doesn’t, your engine will be severely damaged.

In an interference engine, the highest point the piston reaches in its travel is higher than the lowest point the valves reach in their travel. If the timing belt stretches, breaks, or jumps, then the pistons hit the valves, which bend or break the valve head and can break the piston. This almost always results in a destroyed engine that requires a full rebuild or replacement.

In a non-interference engine, the valves can be fully open when the piston is at its highest point, called top dead center. If the belt breaks, the piston can’t hit the piston. The engine shuts down. Non-interference engines are not damaged when the belt breaks, but these engines are not common in modern vehicles.

Is a timing chain different from a timing belt?

A timing chain is like a bicycle chain. The gear’s teeth engage the chain, driving the camshafts with the crank. Over time, chains stretch and can jump time. Chains are far more durable and have about twice the life of a belt. Belts are more common in modern engines that use overhead cams. If you drive a modern economy car, family car, or luxury car, chances are you have an overhead cam engine. Chains are almost always used on cam-in-block engines, which are typically found in trucks.

Timing Belt Warning Signs

A mechanic wearing blue nitrile gloves removes an engine’s upper timing belt cover, exposing the timing belt. — You can remove the timing belt cover at the top of the engine to look at the belt. Some engines only have small windows covered with a plug or sliding door.

Most of the time, timing belts do not give you much warning. They break suddenly. That said, you may be lucky enough to notice one of a few symptoms before a timing belt breaks or jumps time.

Check engine light: Your CEL may light with a timing belt-related code.

Misfires: If the engine misfires or runs poorly, the belt may have slipped.

No-start: If the engine does not start, you may have a broken timing belt.

Decreased performance: If the engine suddenly loses power, your timing belt may have slipped. Drive to a safe location and turn off the engine.

How do you check to see if your timing is broken?

The fastest way to determine if the belt has broken is to open the front timing cover access. This is usually near the top of the engine. See if the belt is loose or missing. You can turn the engine over by hand using a breaker bar and socket on the crankshaft. If the cam gears do not move with the crank, the belt is toast. If there is a hard spot when turning the engine over, stop all engine movements. Never force the engine to turn because a piston may be hitting a valve.

Replacing Your Timing Belt

A mechanic wearing blue nitrile gloves points out the top-dead-center alignment mark on a timing belt gear with his left index finger. — Timing is critical. Each gear is marked with a notch or arrow that points to the top-dead-center (TDC) alignment position.

This is an advanced skill-level DIY job. Most front-wheel-drive and all-wheel-drive vehicles have horizontally mounted engines. Everything is tightly packaged. With this layout, the timing belt is hard to access because the front of the engine is a couple of inches away from the subframe. Longitudinal engines, typically found in pickup trucks, are more accessible. You can remove the radiator and gain a lot of working space.

Getting access to the timing belt is just part of what makes the replacement tricky. It’s easy to get a cam off-time by one tooth, which can kill the engine. The cam and crank gears must not move even one degree during the process.

Check out our video and guide to changing a timing belt - opens in new window or tab. for step-by-step instructions. The job takes between two and five hours.

Cost To Replace Your Timing Belt

A new timing belt and pulleys displayed on a white work surface. — A timing belt kit, which costs about $150 to $300, is the best solution because it comes with the components and gaskets you need.

Most timing belts cost between $50 and $100. A timing belt kit costs about $150 to $300. A timing belt kit is the best solution because it comes with the components and gaskets you need.

Meanwhile, paying a shop to change your timing belt could cost between $500 and $2,000 in labor alone.

You will need a new tensioner to go with the belt. Sometimes, the worn-out belt can damage your water pump and idler pulleys.

If your engine has a hidden water pump driven off the timing belt, you should replace it at the same time. Also, you may need to drain the coolant from the engine. The timing belt replacement takes a significant amount of time. Bundle your repairs if you can.

About the author

Jefferson Bryant

A lifelong gearhead, Jefferson Bryant got his first car when he was two: a Fisher-Price convertible. An industry veteran for over 30 years, Jefferson started in car audio, working his way up to product designer for Rockford Fosgate. He has written nine books and countless magazine articles about automotive technology. Jefferson also produces tech videos on YouTube. His pride and joy is a 1971 Buick GS Convertible with a swapped Procharged Gen V LT1, which he used to drive his newborn kids home from the hospital.

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This article is meant to provide general guidance only. Automotive maintenance, repair, upgrade, and installation may depend on vehicle-specifics such as make and model. Always consult your owner's manual, repair guide for specific information for your particular vehicle and consider a licensed auto-care professional's help as well, particularly for advance repairs.