What Are Engine Valves: Types, Working and Symptoms

Valves are extremely important components in any internal combustion engine, allowing exhaust gases to exit as needed and air to enter the combustion chamber. Therefore, valves play a very important role in any internal combustion engine, completing the fuel combustion process.

engine valves

But due to a lack of information, many people do not have complete knowledge about engine valves, like what engine valves are, how they work, and how many types there are. This article will provide you with information on every aspect related to engine valves.

What Is An Engine Valves?

Valves are important mechanical components in internal combustion engines that control the entry of air and the exit of combustion gases from the engine. When the engine crankshaft rotates, the valves open at the correct intervals according to the position of the pistons to allow the engine to breathe and expel the gases produced by fuel combustion.

Typically, engine valves, usually made of steel or titanium, are fitted in the engine head beneath the rocker arms of the exhaust camshaft and intake camshaft.

How Do Engine Valves Works?

The opening and closing of the valves of an internal combustion engine are controlled by the camshaft, which has lobes along the camshaft that apply pressure against the valve stem during the rotation of the camshaft, causing the valves to open and close at precise times according to the position of the piston. Are closed.

But you need to know in detail how engine valves work. Because if you are not aware of its functioning, you will not be able to understand its importance.

Intake Stroke

During the intake stroke of a four-stroke engine, the intake valve opens to allow the mixture of air and fuel to enter the combustion chamber. The timing of the valve opening coincides with the downward movement of the piston, creating suction that draws the air-fuel mixture into the cylinder. Normally, the intake valve opens as the piston is moving downward, allowing the suction of the piston to draw air through the center of the valve.

Compression Stroke

After the intake stroke, the intake valve closes, closing the combustion chamber. The piston then moves back up into the cylinder, compressing the air-fuel mixture. Both the intake and exhaust valves remain closed during the proper stroke so that the air and fuel mixture can be adequately compressed.

Combustion Stroke

The spark plug then ignites the air-fuel mixture when it is compressed, causing combustion. However, in diesel engines, this process happens without spark plugs. The combustion explosion pushes the piston back into the cylinder, producing power. During this stroke, both the intake and exhaust valves close to prevent combustion gases from entering the chamber.

Exhaust Stroke

Finally, during the exhaust stroke, the exhaust valve opens to allow the combustion gases to escape while the piston moves back up into the cylinder. This allows burned exhaust gases to exit the combustion chamber and enter the exhaust system. This is how the intake and exhaust valves of the engine work.

Types Of Engine Valves

The types of valves in an internal combustion engine depend on the design of the engine. Engine valves can be of different types.

1. Poppet Valve

These types of valves are the ones used in normal engines. Common are used in most internal combustion engines. This type of valve consists of a cylindrical stem with a disc-shaped head that sits against a valve seat in the cylinder head. The valve is opened by the pressure of the camshaft lobe and rocker arm, and the valve is closed by the pressure of the valve spring.

2. Rotary Valve

A rotating mechanism is used instead of pressure to open and close such valves. This type of valve automatically rotates on its axis to open and close a port in the cylinder head, due to which the valve opens and closes.

3. Sleeve Valve

These valves use a cylindrical sleeve that moves up and down within the cylinder head to open and close the ports. The mechanism system of this type of valve is of a different type.

4. Desmodromic Valve

This type of valve uses a mechanical linkage instead of spring pressure to open and close. This allows precise control of valve timing and eliminates valve float at high engine speeds, due to which the valves in the engine can move efficiently.

5. Variable Valve Timing Valve (VVT)

This type of valve uses a mechanical or hydraulic system, rather than spring pressure, to change the opening and closing times. This type of valve uses a hydraulic capsule in the lobe rocker arm of the camshaft to open and close. This allows for better engine performance and efficiency. Almost at present VVT system is being used in most of the vehicle engines.

Symptoms of Bad Engine Valves

Let us know these symptoms of a bad engine valve in detail so that you do not get confused in case of any other engine problem.

1. Loss of Engine Power

If the engine’s valves are worn or the valves are not working properly, the engine cannot draw in enough air and fuel and is unable to exhaust the exhaust gases at the correct timing.

This can result in reduced power and acceleration. For any internal combustion engine to produce power and operate efficiently, the fuel mixture must be successfully ignited in the internal combustion chamber.

2. Engine Backfiring Issue

If the engine’s exhaust valves are not closing properly with the correct timing, exhaust gases can be forced back into the intake system, causing backfiring. Engine backfiring can be a symptom of a damaged engine valve.

3. Low Fuel Efficiency

If the engine valves are damaged and not working properly, the engine is not able to efficiently burn the fuel mixture in the internal combustion chamber, thereby inhibiting the combustion process of the fuel in the internal combustion chamber of the engine. Hence, the engine of the vehicle may reduce fuel efficiency.

4. Knocking or Ticking Noise

When the engine valves are damaged or bent, a strange ticking noise starts coming from the engine while starting it. Because the engine valves are damaged, there is more friction, or the head starts hitting the valve seat.

5. Engine Jerking or Vibration

When the engine valves are damaged, the engine starts vibrating while starting or jerking during acceleration. because damaged engine valves can interrupt fuel combustion in the internal combustion chamber of the engine, due to which the engine starts misfiring, which causes jerks or vibrations.

Causes Of Damaged Engine Valves

  • Engine Valves Breakdown
  • Lack of Lubrication
  • Carbon buildup In Valves
  • Improper Valve Adjustment
  • Engine Overheating
  • Timing Belt Problems
  • Lack of Maintenance


How Many Engine Valves Are There?

The valves of the engine depend on the design of the engine. Some engines have two valves for one cylinder (one intake valve and one exhaust valve), and some engines have four valves for one cylinder (two intake and two exhaust valves).

What Happens When Engine Valves Fail?

Many engine problems are faced due to the failure of engine valves, such as low engine power, misfires and backfiring, smoke issues, and compression problems.

Where Are The 4 Valves Located?

The valves of the engine are fitted in the valve seat in the center of the engine head. The portion of the head containing the valves is located just above the piston.

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