Blog Car Care Advice What Does a Timing Belt Do? (+What Happens When It Fails?)
Car Care Advice

What Does a Timing Belt Do? (+What Happens When It Fails?)

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Timing is of the essence. 
But what does this have to do with cars? 

Your timing belt is essential to your car’s engine, ensuring each process happens on time. 

But what does a timing belt do, and why is it important

This article will address that, along with signs that your timing belt is faulty, when you should replace the timing belt, and the costs involved. We’ll also look at other parts you should check when replacing your timing belt and answer some faqs

This Article Contains:

Let’s get started. 

What Does a Timing Belt Do?

Your timing belt (cam belt) connects the crankshaft and the camshaft, coordinating the combustion cycle of an internal combustion engine. 

The movement of the pistons rotates the crankshaft. The rotation of the crankshaft is transmitted through the timing belt to move the camshaft. The camshaft then controls the intake and exhaust valve activity. 

Here’s what happens within a cylinder:

Each valve and piston must move in a carefully coordinated dance to work effectively without blowing up the engine. 

Note: Your timing belt shouldn’t be confused with your serpentine belt. Your serpentine belt keeps your engine accessories running, and your vehicles timing belt handles the combustion cycle. 

Now that we’ve answered ‘what does the timing belt do?’, we’ll move to what happens should it fail. 

Timing Belt Failure: What Happens?

A modern cars engine can be an interference engine or non interference engine. A non interference engine could survive a broken timing belt without too much damage, but that’s not the case for an interference engine. 

In interference engines, the valves and pistons occupy the same area in the cylinder during different stages of the combustion cycle. This risky design increases efficiency and power, as the reduced volume of the cylinder allows for higher compression.

However, a snapped timing belt will prevent the camshaft from opening the valves in sequence, causing a collision with the pistons and significant engine damage. If this happens, the engine repair cost can be extensive since you might need to replace your cars engine or purchase a new vehicle.

A broken timing belt could be a disaster, but car maintenance can help spot issues early. 
Now let’s look at some indicators of a bad timing belt. 

What Are the Signs of a Timing Belt Going Out?

Imminent belt failure offers a few symptoms:

1. The Engine Misfires

If your engine belt is worn-out, it’ll slip and cannot open and close the cylinder valves properly — affecting the ignition process and causing engine misfires.

2. Ticking Noise From the Engine

What does your timing belt do?
It’s attached to several pulleys connected to the engine’s crankshaft and camshaft. 

The camshaft controls the timing of the cylinder valves and rocker arm assembly. Proper valve sequencing allows constant fuel supply to the combustion chamber. If a timing belt wears out, it may generate a ticking noise in the cars engine. 

However, the engine may also produce this clicking noise due to low coolant or oil pressure.

3. Oil Leaks From the Front of the Motor

This is a common bad timing belt symptom — or rather, if you have a bad timing chain. 

The timing belt cover protects your vehicles timing belt or chain from grim, debris, and gravel. In vehicles with timing chains, the timing belt cover also secures the front section of the engine block, so the timing chain can receive lubrication.

Oil around the engine may indicate a leak from your timing belt cover, meaning that it has loosened. Oil can also leak if the gasket between the timing belt cover and the engine block is cracked or blown. This may overheat the engine and cause more expensive repairs.

4. More Smoke and Fumes Than Normal

If your vehicle emits more smoke than usual, there’s a high chance of a bad camshaft. Since your camshaft controls the exiting of exhaust gasses, a belt failure might delay or restrict that process. 

In this condition, the engine needs to work harder than expected. Because of this overload, your car emits more exhaust fumes than usual.

5. The Engine Won’t Turn Over

If your cambelt malfunctions, the engine can’t ignite the fuel or turn over properly. You’ll hear the starter motor running when you turn the key, but fuel won’t fully ignite.

A damaged timing belt badly affects the performance of the crankshaft and camshaft, and the engine won’t turn over.  

Timing belts usually get worn while driving, and if the timing belt breaks, you shouldn’t drive your vehicle. This can severely damage cylinder head components such as cylinder head valves, pushrods, and rocker arms.

These symptoms are easy to miss and hard to diagnose since other problems can also cause them. So when should you get a new timing belt?

When Should I Replace My Timing Belt?

The suggested timing belt replacement period is between 60,000 miles and 90,000 miles. It’s essential to get your timing belt replaced per your owner’s manual. Putting off a belt service is risky and could lead to significant damage. 

That said, would a new timing belt dent your wallet?

How Much Does it Cost to Replace a Timing Belt?

A new timing belt can cost $400 – $1,000 since it requires 3 to 5 hours of labor.

However, once a faulty belt causes damage to the pistons and other parts — it can cost you more than $2,000.

Your cars timing belt comes into contact with other parts that you should also schedule service for when replacing your cambelt. 

What Other Parts Should Be Checked When Replacing the Timing Belt?

Take advantage of the timing belt replacement by checking any engine component that comes in contact with the belt. Schedule service for parts like: 

A. Drive Belts

Get your drive belt(s) checked when replacing the timing belt. A faulty drive belt can cause your car to overheat and affect your A/C and power steering. Have an old and cracked drive belt serviced by auto repair professionals. 

B. Water Pump

Your water pump has a weep hole where water leaks if it goes bad. Even if it’s not dumping water at the time, there could be a trail of antifreeze or deposits from where it’s been leaking.

During auto repair, you’ll have to remove your cars timing belt to get most water pumps off. To save money, you should replace the pump if it leaks while the timing belt is uninstalled. 

C. Oil Seals

The oil seals behind the cam and crankshaft gears can leak due to aging and wear. Leaking oil seals can deteriorate your timing belt, causing it to break prematurely. This may result in a bent valve and another belt replacement.

To replace the oil seals, you’ll need to take off the timing belt. So its easier to replace them together with the belt.

 D. Timing Belt Tensioner

Your timing belt tensioner can sometimes be faulty or worn. The bearings on your belt tensioner could even be defective. Additionally, a belt tensioner can have a hydraulic tensioner working with the tensioner bearing – which can also leak.  

If you notice these parts are faulty, fixing them together when the timing belt breaks is best.

So, to avoid catastrophic engine damage, look into the mentioned parts during a belt replacement. Moving on, we’ll discuss some timing belt FAQs. 

2 Timing Belt FAQs

Here are the answers to two frequently asked questions regarding your timing belt: 

1. What is a Timing Belt Made Of?

Essentially, it’s a rubber belt. But it’s more than just a rubber timing belt. 
Modern timing belts consist of synthetic rubbers with high-tensile strength reinforcing cords made of Kevlar, polyester, or fiberglass.

This rubber belt has specially shaped teeth cut and sized to connect properly with the crankshaft and camshaft pulleys. The teeth profile gives you either curvilinear or trapezoidal timing belts. The trapezoidal timing belts have trapezoidal-shaped teeth. 

Since oil can damage rubber, engines with a rubber timing belt are typically constructed in a “dry” setup. This means that engine oil or coolant doesn’t interact with the belt — except for  timing chains that have oil flowing over them to lubricate and protect the parts.  

2. How Does a Timing Belt and Timing Chain Differ? 

Depending on the model, your vehicle might have a timing chain instead of a timing belt. Your owner’s manual will confirm if you have a timing belt or chain

A timing chain or belt has the same function, but the chain is metal instead of rubber. Timing belts became popular after being introduced in the 1960s, as they were light and quiet. 

However, modern cars have returned to using the chain thanks to design improvements and a long lifespan. So, if your vehicle has a timing chain and not a timing belt, you may be able to go longer before replacing it. 

Closing Thoughts

A timing belt is an essential engine component of an internal combustion engine. A snapped timing belt could be disastrous, but it can be prevented.

By always trusting professionals to handle any belt service or timing belt replacement. 

Professional mobile mechanics like AutoNation Mobile Service are available seven days a week for car maintenance, fleet services, a simple engine oil check, and more. 

AutoNation Mobile Service offers upfront pricing, and repairs come with a 12-month | 12,000-mile warranty.
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