Know your Car Engine -Timing Belt

Everything you need to know about timing belt or chain

Two engine components are interconnected with a timing belt, which is also known as timing chain, or cambelt. The part synchronizes the rotation of an engine crankshaft and camshaft in order to open and close the engine’s valve at proper timing to ensure unobstructed combustion. Now you can see the essence of a timing belt in the engine combustion process, since valve open and close for the intake of air/fuel mixture and escape of exhaust gas.

The timing belt is made of rubber with hard teeth that key with the cogwheels of the crankshaft and the camshafts. The component sometimes powers the oil pump, water pump, and injection pump depending on the engine design. Timing belts are referred to a toothed belt or a drive belt designed with teeth on the inside surface. While a timing chain is a roller chain but the manufacturer use either of them to achieve the same purpose.

The model of a vehicle determines either a timing belt or chain is used. the chain might be used instead of a drive belt, they still serve the same purpose. The reason why the timing belt is widely used is that it’s lighter and quieter ever since it’s introduced in the 1960s. However, modern engines now work with timing chains as they can serve for a long period of time.

Today we’ll be looking at the definition, functions, parts, diagram, types, and working principle of a timing belt. I’ll also explain the construction and design as well as symptoms of a bad timing belt.

Timing Belt Definition

A timing belt is a component used in an internal combustion engine to synchronizes the movement of the crankshaft and camshafts. It is designed with a precise hard tooth that interlocks with the cogwheel of a crankshaft and the two camshafts. Because of the accurate teeth of a drive belt, the intake and exhaust valves open and close in time with the pistons.

The construction and design of a timing belt is typically a rubber with high tensile fibres. The entire belt is constructed in sturdy material such as moulded polyurethane, neoprene or welded urethane of various level. the tooth may be non-standard or metric pitches. A pitch is a distance between the centres of two adjacent on the timing belt.

Rubbers degrade with higher temperatures, and when come to contact with oil. Timing belt lifespan is reduced in hot and oil leaky engines. Though newer and expensive belts are made of temperature resistant materials such as “highly saturated nitrile”. Also, water or antifreeze can greatly affect the life of the reinforcing cords, making the need for special precautions for off-road applications. This is why most engines are highly in the seal.

Older timing belts usually experience a high rate of wear due to their trapezoid shaped teeth. Well, most manufacturers employ newer techniques by making the teeth curve which makes it quieter and lasts longer.

Functions of Timing Belts

Below are the functions of timing belts or chain in automotive engines:

· The timing belt allows the achievement of the combustion process as the control of the piston and valves relies on it.

· It connects the crankshaft and the camshaft together to control the valve operation.

· Timing belt ensures precise synchronize opening and closing of the engine’s valves.

· Some other engine components such as water pump, injection pump, and oil pump.

· The timing belt uses the same combustion mechanical energy to control the valve. This means no external source is included.

· Another function of a timing belt or chain is that it prevents the piston from striking the valves on a critical level.

A timing belt is just a single device but connects different parts such as the camshaft sprocket, timing belt idler pulley, upper balance shaft sprocket, water pump pulley, timing belt tensional roller, balance idler roller, lower balance shaft sprocket, camshaft belt drive gear, balance belt drive gear, and balance belt tensioner roller.

Timing belt diagram below gives more detail:

Types of Timing Belt

There is a lot to be considered when stating the types of a timing belt as they can be determined by the following explain below;

· Pitch selection

· Pulley selection

· Pulley drawing

· Belt selecting

· Shaft selecting

· Design assembly

Metric Dimensions Timing Belt

· Trapezoidal tooth shape with metric dimension.

· Round tooth shape with metric dimension.

Imperial Dimensions Timing Belts

All these must be considered before listing the types of timing belts but most vehicle manufacturers have a standard design for a specific model of vehicle.

Working principle

Timing belts do their working in a precise and timing manner. It is the reason why the engines combustion process is possible even though the power to rotate the crankshaft. it then synchronizes the camshafts which allow the valve to open and close so that the intake of air and fuel can enter the combustion chamber. The exhaust valve is also controlled by this rotation so that the exhaust can escape. this process is done in harmony.

As the camshaft and crankshaft work in coordination, crankshafts are designed to operate half the speed of the camshaft. For instance, two turns of the crankshaft result to a turn of the camshaft. The timing belt requires tension to properly operate, which is why timing belt tensional is design. Modern vehicles use automatic timing belt tensioners that do not require adjustment. The older vehicles would always need adjustment from time to time as the belt becomes loose. A loose timing belt will force the timing out of range, which is why the problem should be avoided. Timing is so important that if one movement escape, it can affect the efficiency of the engine leading to loss of power, misfires etc.

Symptoms of a bad or failing timing belt or chain

Below are the symptoms of a bad timing belt or chain that need replacement:

· Engine power is decreased

· Engine overheating

· Trouble starting the engine

· Vibrating or shaking of the engine

· Oil leakage

· Ticking noise from the engine

· Engine light on

· Engine misfiring

· Squealing or rubbing noises from the belts.

How to Replace Timing Belt, Timing Balancer, and Water Pump

A timing belt is an essential internal engine component that links the crankshaft and the camshaft to ensure adequate sync rotation and enable the cylinders to fire appropriately. Timing belts are made of strong rubber nylon-reinforced cords that can stand the taste of time. Despite the material utilized in manufacturing the timing belt, it is subject to wear out or break due to the incredible force that it links together and will eventually need to be replaced. Your engine will not run properly without a fully functioning timing belt. Hence, you should know the symptoms of the bad timing belt.

Not all cars utilize a timing belt. The timing belts are commonly seen on most small cars and trucks that have a small engine compartment. Timing belts have predetermined dates to replace them, but there are signs you need a new timing belt.

A timing belt is an essential internal engine component that links the crankshaft and the camshaft to ensure adequate sync rotation and enable the cylinders to fire appropriately. Timing belts are made of strong rubber nylon-reinforced cords that can stand the taste of time. Despite the material utilized in manufacturing the timing belt, it is subject to wear out or break due to the incredible force that it links together and will eventually need to be replaced. Your engine will not run properly without a fully functioning timing belt. Hence, you should know the symptoms of the bad timing belt.

Not all cars utilize a timing belt. The timing belts are commonly seen on most small cars and trucks that have a small engine compartment. Timing belts have predetermined dates to replace them, but there are signs you need a new timing belt.

Common Symptoms of a Bad Timing Belt

A few timing belt warning signs indicate you have a worn-out or broken timing belt, which will require you to replace or contact a professional mechanic to replace it and diagnose other internal components.

Engine Misfires:

A worn-out timing belt can affect your engine firing order. As the timing belt drives the cam and the crankshaft in sync rotation, a worn-out tooth can cause the timing belt to jump a tooth on the cam or crankshaft sprocket and cause the cylinders to open randomly. If this happens, you can lead to engine blow-by if not replaced on time.

Ticking sound from the engine:

As indicated above, the timing belt is attached to sprockets that drive the cam and crankshaft in an engine. When the timing belt is worn out or is aging, it’s honestly going to malfunction. You might hear a ticking sound from the engine. Now, be aware that if your car has a low engine oil, you’re going to hear a ticking sound as well, because you’re going to hear those lifters lifting.

So, it’s not like you’re going to take a new timing belt and put it once you hear a ticking sound, no. It means that you should look into it a little bit further. Be aware of your timing belt while inspecting it, and you don’t want to get too close to it if it’s moving. The timing belt is a moving component of your car, so keep a distance while looking into it when you hear ticking from the engine.

Engine won’t start:

Another bad timing belt symptom is that your engine won’t start. A timing belt plays a significant role in your engine starting. If your timing belt is wholly gone, missed some teeth due to slippage, or has broken, your engine won’t start. You might hear the starter kicking. You might hear the starter trying to start the engine, but the engine won’t start.

However, there are so many things that could cause your engine not to start. So, if your engine doesn’t start, you might need a new battery, a new alternator, a new fuel pump, or a new starter. There are so many other things that could cause your engine not to start.

The actual timing belt looks worn out:

you could look at the timing belt. There are good visual indicators in most engines. Just look through the indicators when the engine is off. You will get a visual indication of whether the timing belt is worn out or not.

Timing belts are made of strong rubber materials, but they are made to wear out and get replaced. If it looks worn out, chances are the belt is long gone. You have to replace it because you don’t want to be stranded on the side of the road.

You have exceeded the recommended mileage:

Last but not least, the fifth symptom or sign is that you have exceeded the recommended mileage to replace your timing belt. Check your owner’s booklet,

and see the recommended date to change your timing belt. If you have exceeded the recommended date, just get the cash and replace it. Depending on your car’s make and model, you can replace the timing belt yourself or contact a professional mechanic to replace it.

How to Check Timing Belt

The timing belt is the most crucial replacement component in your car. As we all know, timing is everything! Let’s see how to know when to replace the timing belt. A good rule of a term is to check it every 10,000 miles and replace it strictly as the manufacturers recommend in your service booklet, usually somewhere between 60,000 to 90,000 miles. There are two ways to check the timing belt. They are as follows:

Visual inspection:

In some vehicles that utilize timing belts, there are built-in inspection ports. It means there is usually a small cover on the timing cover that you can easily remove without removing the entire timing cover when carrying out a visual inspection. These covers are typically tightened with two 100mm bolts.

To inspect your timing belt, lose the two bolts and take off the cover. Take a close look at the timing belt, check for any crack, and check for any missing tooth. A single missing tooth can cause catastrophic engine damage, and that could cost you up to 750 dollars of repair. So, it’s a good idea to check your timing belt every 10,000 miles. You will also rotate the timing belt a little bit and see if it is too loose. Because if it is loose, it will cause a bad timing belt noise.

Using a Timing Gun/light:

It will be a total waste of time if you take off your engine to check your timing belt and find out that it is still good. So, the best way to avoid this is by checking your timing belt with a timing gun. You can also use the gun to check your timing chain as well.

To inspect your timing belt with a timing gun, you will have to connect your timing gun terminals to your battery terminals. You want to connect it positive to positive and negative to negative. Then, take the inductor sensor, put it on the number one plug wire, and start your car.

Now, as a mechanic or a DIY, take white paint and paint the timing mark on the pulley so it could be easy to read when you flash the light on it. Flash the light on the pulley while the engine is running and rev the engine. If the mark stays in one place, it means your timing belt or timing chain is still okay. But if it’s jumping as you’re flashing the light, it indicates the timing belt is bad.

Procedure to Change Timing Belt

As per many OEM's, your timing belt needs to be serviced every 50,000 to 80,000 miles. While you're in there, there are a few other important things to address like the timing balancer and the water pump. This article will guide you through the process of replacing the timing belt, timing balancer, and the water pump on a Car .

Timing belts and water pumps are wear items. They need regular servicing, and are critical components to the longevity of your vehicle. One controls how the motor stays in sync under operation, while the other one controls how effectively the motor is cooled. They are equally important, and require special attention that requires advanced mechanical knowledge. But fear not weekend DIY-ers, this article will help you perform this crucial job on your own.

Materials Needed

• 1/4” drive ratchet, 3" extension, 6pt metric sockets and deep sockets (8mm-12mm)

• 3/8” drive ratchet, 3", 6" extensions, 6pt metric sockets and deep sockets (10mm-19mm)

• 1/2” drive ratchet, 18" breaker bar, 19mm 6pt socket, and 20" extension

• Metric combination wrenches (8mm-17mm) (optional)

• Crankshaft pulley holding tool

• Torque wrench (able to torque to 181 ft/lbs.)

• P1 Phillips head screwdriver

• P2 Phillips head screwdriver

• Small slotted screwdriver

• Large slotted screwdriver

• Regular pliers

• Needle nose pliers

• Floor jack

• Jack stands

• Block of wood

• 5’ steel pipe

• 18” steel pipe

• Funnel

Parts Needed

• Timing belt

• Tensioner

• Belt adjuster spring

• Water pump

• Valve cover gasket set

• Cam seal plug BLOX 3 ring from an OEM 12513-p72-003

• Accessory belts (ac/alt/ps)

• 1 gallon antifreeze (50/50)

Step 1 – Prepare vehicle for service

Before tearing into this job, you want to make sure it's positioned and ready.

• Disconnect the negative (black) terminal on the battery.

• Jack car up using hydraulic jack and jack stands.

• Remove the splash cover (seven bolts and push clip).

• Remove the front wheels.

• Secure the e-brake, and chock rear wheels.

Vehicle secured on stands.

Undertray removed

Step 2 – Remove power steering belt

In order to begin this job, start by removing one of the belts.

• Loosen the adjusting bolt.

• Remove the mounting nuts.

Power Steering bolt and tensioner

Pro Tip

The power steering pump can be removed from its bracket to gain more room. The hoses do not need to come off.

Step 3 – Remove the alternator

The alternator as well as its related belt will need to come off in order to gain more clearance to the timing belt and water pump.

• Loosen the adjusting bolt (yellow).

• Remove the lock nut (green).

• Remove the mounting bolt (red).

• Remove the alternator belt.

• Remove the alternator terminal and wires. Move them to the side.

Alternator bolts.

Step 4 – Remove driver's side engine mount

To gain more clearance, this mount will need to be removed.

• Secure the oil pan with the block of wood, and jack.

• Remove the bolt, and remove the engine mount.

• Remove the oil dipstick and tube.

The block of wood equally distributes the pressure of the jack across the pan.

Step 5 – Remove valve cover

This is another necessary step in order to ensure the motor is timed correctly after the belt and pump are replaced.

• Remove the spark plug wires, and set aside.

• Remove the cruise control cable from the clips on the valve cover (green).

• Remove the PCV from the valve cover (yellow).

• Remove the hose from the valve cover to the intake tube (blue).

• Remove the five bolts from the valve cover, and remove (red).

Top end items that need to be removed.

Step 6 – Remove crank pulley and bolt

This is one of the last components of the drive train that needs to come in order to remove the last belt.

• Use a crankshaft pulley holding tool to remove the crankshaft pulley bolt.

Crank pulley exposed.

Pro Tip

Using a breaker bar and a large pipe can provide the leverage needed to break the bolt loose.

Step 7 – Remove upper and lower covers

To access the timing belt and dampener, these covers will need to come off.

• Remove the bolts (red).

• Remove the adjusting nut (yellow).

Upper timing cover

Lower timing cover.

Pro Tip

Be sure to keep the seal around the adjusting nut (yellow).

Step 8 – Remove timing balancer tensioner and belt

Now that the timing belt and balancer are exposed, you'll want to ensure the TDC. Make your marks (if necessary), then remove the belt and balancer.

• Ensure the TDC. The green arrow points to the plastic cover, which lines up with the "up mark" in yellow. TDC marks are in red

• Loosen the adjusting nut in red

• Push belt tensioner down. The yellow in Figure

• Tighten the adjusting nut, and remove the timing belt.

Timing belt TDC marks.

Timing tensioner.

Pro Tip

Before moving on to the next step, it's wise to drain the coolant. Place a pan under the car, and turn the petcock on the bottom of the radiator to release.

Step 9 – Remove water pump

Now that the coolant has been drained and the timing belt as well as the balancer have been removed, the water pump can come out.

• Remove the bolts in red

Water pump cover.

Water pump removed.

ro Tip

Be mindful of the spring hooked to one of the bolts as it is connected to timing balancer belt tensioner.

Step 10 – Installation is reverse of removal

Now that all the wear components have been fully removed, the new components can be installed. Careful consideration should be taken when installing the components because you will need to ensure timing is set correctly (as previously marked).

• Install the new water pump with the gasket.

• Ensure TDC is at Position 1 at the crank.

• Install the timing belt drive pulley.

• Install the tensioner.

• Install the water pump pulley.

• Install the camshaft pulley.

• Loosen and tighten the adjusting nut to tighten the tensioner belt.

• Install the timing balancer belt pulley and lower cover. Then, tighten the bolts.

• Install the crank pulley and bolt.

• Rotate the crank pulley 5-6 revolutions counterclockwise, and ensure TDC marks are still in line.

• Install the upper cover and tighten bolts.

• Install valve cover and tighten bolts.

• Reconnect PCV and hose to intake tube.

• Re-install spark plug wires.

• Torque everything to spec.

• Refill the coolant.

• With cap off, run the car until it reaches operating temperatures.

• Re-install the radiator cap, and run the car again to observe any leaks.

In conclusion, timing belts is a rubber component with tension that help the rotation of a variety of component in an engine. The work in a precisely, as the valve make use of it in such manner. It connects the crankshaft and camshaft together; the crankshaft receives power from the piston which attached to a connecting rod. In this article, we saw the functions, working, and types of timing belts or chains.

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