How does Cambelt work? | Signs of Bad Timing Belt

The cambelt is the most important part of your vehicle. It is a rubber belt with teeth that ensures the proper rotation of the camshaft and crankshaft in perfect synchronization. It is mainly used to connect the camshaft with the crankshaft. The proper working of the timing belt is very important for the efficient working of the engine. This article deeply explains the bad timing belt symptoms, causes, and how to replace it.

What is a Cambelt?

A cambelt is also called a timing belt. In reciprocating engines, the cambelt is used to ensure the rotation of the camshaft and crankshaft in proper synchronization.

The timing belt or cambelt ensures proper opening and closing of the engine valves at an accurate time according to the reciprocating motion of the piston. As the timing belt fails, the engine can’t generate power and can’t run the vehicle. 

The rubber is most commonly used for the construction of the cambelt. A synthetic compound is also mixed with rubber to improve its durability. The belt has teeth (grooves) on one side to improve the retention of various shaft heads within the motor. If the belt doesn’t have these grooves, it can slip at any time.

Cambelt, timing belt

This type of belt is installed in a specific arrangement along one side of the engine. The main function of the camblet is to synchronize the bottom half of the engine (crankcase and piston) with the top half (cylinder head and valves).

With the passage of time, the belt stretches; due to that, it fails without warning. In some cases, you can hear a rattling noise in the timing belt area when the engine is idling. This indicates wear and tear on the belt tensioner or idler pulley and may result in belt damage. This is a factor that may cause premature belt failure.

Construction of Timing Belt

The maximum timing belts are made of rubber, but some types of timing belts are also made of neoprene or polyurethane. The toothed surface of the belt is strengthened with a fabric cover while the belt structure is strengthened with a fiber cord (as tension member).

cambelt construction

As we know that rubber deteriorates due to extreme temperatures and oil leakage. As a result, the engine overheating or leaky engine oil issues start to appear, reducing the service life of your engine’s timing belt.

In addition, the coolant or water leaks also lead to the failure of the belt. Therefore, it is vital that your belt, which may be damaged due to water, must have the ability to remove the water fast.

The conventional belts have trapezoid design teeth, which increases the wear rate of the teeth. The latest belts have curved teeth that have a quiet operation and long service life. 

Manufacturer-specification belts can stretch at high speed, delaying the cams and retarding the combustion process. The strongest aftermarket belts don’t stretch and stay the same over time. The wider belts increase strength, while the narrow belts reduce friction and weight.

Function of Timing Belt

The timing belt or cambelt is one of the most important parts of the IC engine. The main function of the timing belt is to synchronize the rotation of the engine’s camshaft and crankshaft.

It also regulates the timing and order of opening and closing the engine cylinder valves. It also ensures the rotation of the camshaft and crankshaft at a proper synchronous.

  1. It regulates the proper closing and opening of the cylinder valves so that the engine burns the fuel properly.
  2. The crankshaft moves the piston upward and downward simultaneously.
  3. Tight timing can damage pistons, valves, and other engine parts.

Signs of a Bad Timing Belt

When the timing belt or cambelt goes bad, it produces one or more of the below-given symptoms:

  1. Shiny Belt Rubber
  2. Cracks on the Belt
  3. Peeling
  4. Loose Belt
  5. Slipping Belt 
  6. Misfiring
  7. Ticking or Clicking Noise
  8. Engine Won’t Start
  9. Oil Leak Near the Engine
  10. Excessive Smoke from Tailpipe

Let’s discuss these symptoms in detail:

1) Shiny Belt

The shiny belt rubber is one of the first signs of a bad cambelt. This is a clear symptom of stressed rubber that represents that your belt will break very soon. Therefore, as you observe this sign, immediately replace your belt. In this way, you can save yourself by an expansive repair.

shiny belt rubber

2) Cracks On the Belt

The cracks on your belt rubber represent that it’s time to replace the belt with a new one. Cracks may start to produce on your timing belt if you don’t replace it for a long time.

Cracks on timing belt

The cracks show that the rubber is in poor condition and can break at any time.

3) Peeling

With rubber, peeling is like a crack. This symptom shows that the belt material has been damaged and quickly losing its integrity. Therefore, you must replace your belt as soon as possible.


4) Loose Belt

The loose belt shows that you need to replace it. When the belt rotates, such as when the engine starts, the movement requires moderate tension.

Loose cambelt

A loose timing belt slips again and again due to that your engine won’t be able to work efficiently. As your timing belt is loose, you must tighten it or replace it immediately.  

5) Slipping Belt

The belt slipping is one of the famous symptoms of a bad timing belt. The belt slip shows that your belt teethes are damaged, and you need to replace your belt.

6) Engine Misfiring

A bad belt can affect the air-fuel ignition process and may cause engine misfiring. If your engine belt is worn out, it will slip due to that it will be unable to open and close the cylinder valves properly.

engine Misfiring

If the cylinder valves don’t open and close properly, the engine will not properly burn the air-fuel mixture and cause misfiring. Engine stalling is also a sign of a malfunction which shows that you must inspect your engine quickly to avoid serious engine damage.

Your engine cylinder may also be misfired due to a bad ignition coil, a faulty fuel injector, a bad spark plug, or a bad O2 sensor. Therefore, it is compulsory to properly diagnose the system to find the main issue. 

7) Ticking or Clicking Noise

Ticking Noise, symptoms of bad timing belt

If the engine of your car makes a clicking noise, it means that your timing belt has a serious problem. The vehicle’s cambelt is connected to a series of pulleys that connect to the crankshaft and camshaft of the engine.

The crankshaft transfers its rotary motion to the connecting rod, which is further connected to the piston. This piston reciprocates in the combustion chamber.

The camshaft controls the opening and closing timing of the cylinder valves and rocker arm assembly. The proper opening and closing of the cylinder valves ensure the proper fuel supply to the combustion chamber.

With time, the timing belt starts to wear out, and it may generate a clicking noise in the engine. The engine may also produce this clicking noise due to low coolant or low oil pressure.  

8) Engine Won’t Start

In case of a bad or damaged cambelt, the engine can’t ignite the fuel or turn over properly. In other words, you can hear the starter motor running when you turn the key, but it will not completely ignite the fuel.

Engine Won’t Turn Over

The cambelt is responsible for properly operating the crankshaft and camshaft. When the timing belt becomes faulty, it badly affects the performance of the crankshaft and camshaft due to that your engine won’t start.  

If the timing belt breaks, you can’t drive the vehicle. When your timing belts are damaged while driving, they may lead to severe damage to cylinder head components such as valves, pushrods, and rocker arms.

9) Oil Leak Near the Engine

An oil leak near the engine is one of the most famous symptoms of a bad timing belt. If you see oil around the engine, you may have a leak in your vehicle.

A series of nuts and bolts are used to secure the cover of the timing belt. With time, these nuts and bolts may be loose due to that the oil leaks through the belt.

Oil Leak Near the Motor

Oil can also leak if the gasket between the belt cover and the engine block is cracked or blown. This may overheat the engine and cause more expensive repairs.

10) Excessive Smoke from the Tailpipe

If your vehicle is emitting a lot more smoke than usual, there are high chance that your vehicle has a bad timing belt. When your vehicle’s cambelt becomes faulty, the engine needs to work harder than normal. Because of this overload, your car starts to emit excessive smoke from the exhaust system.smoke from tailpipe

If you keep driving with a damaged timing belt, it may cause an expansive repair.

Causes of Timing Belt Failure

The following are the causes of the timing belt failure:

1) Misalignment

Misalignment is one of the most famous causes of a faulty timing belt. Tensile failure or uneven tooth wear may cause of misalignment.

As the alignment between the timing pulley and shaft is disturbed, it may damage your timing belt badly. The proper alignment of the timing pulleys and shaft increases the service life of the belt.

Solution: Regularly inspect the alignment of your vehicle shaft and timing pulleys and ensure their proper alignment. The proper alignment prevents you from an expansive repair.

2) Excessive Load

If the teethes of the belt are shearing, the high load may damage the belt. Unnecessary or impulsive loads can lead to excessive tooth wear or tensile fracture. To fix this, you need to redesign the drive.

Solution: Regularly inspect the condition of your belt teeth and don’t put more load than the capacity of the belt.

3) Under-tensioned Belt

The tooth skipping, also known as “ratcheting,” can occur due to insufficient belt tension. Insufficient tension may result in uneven or excessive tooth wear and extreme drive noise.

Solution: Use a tension gauge to set the correct tension on this timing belt.

4) Weak Drive Structure

A weak drive structure is one of the main causes of timing belt failure. If the transmission vibrates extremely or the timing belt is significantly affected by belt stretch, it means that you have a weak drive structure.

Solution: By reinforcing the drive structure, you can fix this issue.  

5) Damaged or Worn Pulleys

A worn or damaged pulley may affect the belt. The damaged pulleys may reduce the service life of the belt. Worn teeth can lead to belt damage and wear. Nicks and grooves may also damage the belt.

Solution: Check and replace pulleys that have signs of wear.

6) Debris in the Timing Pulley or Drive

The solid debris has the ability to damage the belt and pulleys badly. Contamination on the belt teethes may wear the belt, and oil may corrode the belt material.

Solution: As you notice dirt on your belt, use a stiff brush to remove dirt and rust. Wipe off grease and oil. Dirt may cause any of the timing belt failures mentioned above. Therefore, clean the timing pulleys and put a shield around the body of the drive!

How to replace the Timing Belt?

The timing belt replacement process is very easy. Follow the below-given steps to replace the timing belt:

  1. The car has two belts (power steering belt and fan belt) that house the water pump and timing belt. Therefore, first of all, you need to remove these belts to remove the cambelt or timing belt.
  2. Next, eliminate the timing case and crank pulley covering the belt.
  3. It is best to throttle the cogs before removing the crankshaft pulley. In this way, you will be able to reassemble the parts easily.
  4. After all of these steps, you can easily remove the timing belt.
  5. Next, remove the water pump. Before you do this, make sure there is a bucket under the car to catch the coolant.
  6. Reassemble the engine with a new timing belt and water pump.
  7. Now, refill the cooling system with fresh, high-quality coolant.
  8. After replacing the belt, perform a test drive to check the performance of the new belt. 

Advantages of Cambelt

  1. It improves the performance of the engine.
  2. It ensures the proper opening and closing of the cylinder valves.
  3. The timing belt connects the crankshaft and camshaft.

FAQ Section

When to replace the cambelt?

The cambelt age or replacement period depends on the vehicle model, the brand of the belt, and how much you drive the vehicle. That’s why there is no specific time frame when to replace it. However, you should replace it more than once over the course of the car service life. Maximum manufacturers suggest to replace the camblet after a set number of miles or years. Maximum manufacturers suggest to replace the timing belt anywhere between 39,000 and 100,002 miles or 4+ years.

What are the symptoms of a bad Timing Belt?

  1. The engine won’t start
  2. Smoke from tailpipe
  3. Shiny belt
  4. Cracks on the belt
  5. Peeling
  6. Oil leak near the engine
  7. Loose belt
  8. Belt slip
  9. Misfiring
  10. Ticking or clicking noise

What is the function of the timing belt?

The main purpose of the timing belt is to turn the camshaft and properly open and close the cylinder valves. It ensures the opening of the valves at exact times.

What is the replacement cost of the timing belt?

The timing belt or cambelt replacement cost varies according to the type of vehicle, the area where you live, and the type of brand. The average replacement cost of the cambelt is between $290 and $500. The labor cost also varies according to the type of engine.  

Where is the timing belt located?

In most vehicle models, the timing belt is typically located within the timing cover, positioned near the front of the engine. It is typically made of rubber. However, if you observe a more robust metal construction, it means your vehicle contains a timing chain instead of a timing belt.

Can I drive with a broken timing belt?

No, it is not recommended to drive with a damaged timing belt. If your timing belt is damaged during driving, you should stop the vehicle and replace it immediately; otherwise, it may lead to severe engine damage. Its crucial role is to maintain synchronization between the engine’s valves and pistons. When the timing belt breaks, this synchronization is lost, causing the valves to fall out of harmony with the pistons. Consequently, they may collide, resulting in the bending or breaking of valves and potentially causing extensive harm to your engine.

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