Car engine sounds (What causes them?)

In this brief article, we analyse the various sources of car engine sound.We also discuss what is normal and what is not, with respect to engine noise.



What is Car Engine Sound?


Car Engines are mechanical devices that consumes fuel to produce mechanical work.In the process of their operation they produce sound.This may be due to the burning of fuel or the vibration of parts.Over the years car manufacturers have designed engines to operate more quietly.Yet, some amount of engine noise is unavoidable.

Reasons of Car Engine Sound



Being a prime mover of the car, the engine contains a number of moving parts.Besides it also has the job of converting fuel to mechanical energy.Thus making some amount of sound is perfectly normal.However,.It is only when the noise reaches intolerable levels that one should be concerned about the engine health.

The major sources of engine sound are:


1.The ignition and burning of fuel.


The burning of fuel basically is an explosion taking place in the combustion chamber of the car engine.It is this explosion which is the reason for the running of the engine.Thus,some amount of noise is inevitable from the car engine.


2.The motion of parts


Car engines have numerous parts that need to work in tandem to produce useful mechanical work.
These parts such as the piston, connecting rod, crankshaft,camshaft and valves etc move according to their required job.This causes engine sound.

While the above sounds are normal and not a cause of worry,there are certain noises that represent a fault in the engine and warrants attention.

3.Type of the engine


The sound of the engine is also dependent on the type of fuel used in that particular engine,i.e,  whether the engine is run on petrol or diesel.
Petrol engines are known to be more silent and less vibratory in operation than diesel engines.Also if the engine is turbocharged/supercharged, there is a good chance that you will hear the sound from of the components.

Abnormal Car Engine Noises:



The car engine, being a mechanical device, produces some sound during its operation.This is inevitable despite the unending efforts of car manufacturers to reduce this sound. However, there are some sounds that one should never ignore.These abnormal sounds ae symptoms of problems with the engine.Some such sounds are:

1.Knocking:


Knocking of the engine is a phenomenon that occurs due to improper combustion taking place in the engine cylinder.The most common reason for knocking if car engine is the usage of a petrol with non standard octane number.Poor valve timing is another major cause of knocking.This is a serious issue and begs for immediate redressal.


2.Worn out bearings:


Bearings are fitments that reduce friction between moving parts. A faulty bearing fails to reduce friction and can cause undesirable noise in the car engine.

3.Loose or worn out belt:


A belt drive transmits rotary motion between different parts of the car engine.A poor or worn out belt can affect the vital functions of the engine as well as create a squealing noise in the engine..


4.Low oil level:



The engine oil is perhaps the most important lubricant of any car.Not having enough oil affects the lubrication of the engine.The engine stops running smoothly as the friction between moving parts increase.This can cause abnormal noise.

5.Crankshaft issue:


A damaged or loose crankshaft bearings can hamper the rotary motion of the crankshaft.This can cause an abnormal sound from the car engine.


6.Valvetrain noise:



The intake and exhaust valves are responsible for delivery of air-fuel mixture into the engine and removal of products of combustion from it.They are operated by lifters which can cause an abnormal lifting noise if they are improperly aligned.With increased deposition of dirt and varnish around the lifter, their operation is constrained

The remedies :

Any abnormal noise emanating from the engine is not a thing to ignore.It is indicative of the fact that not everything is fine in your car engine.Thus it is essential to identify the reason behind the noise and get it addressed immediately.

1.The issue of knocking:



Knocking occurs when combustion in the engine is abnormal.This phenomena is observed particularly in the petrol engine.Knocking can be fixed by using the recommended fuel (Octane Rating), Replacing the timing belt, replacing the bearings.Ensuring that combustion is clean and complete is essential for reducing the noise.


2.Depleted Oil in the sump:



Oil levels should always be monitored and top up should be done without delay.Upgrading the engine oil to a better quality makes the engine run smoothly and reduces the undesirable noise.


3.Worn out parts:


Every mechanical component has a lifetime. Over the years they are subjected to fatigue and can not perform optimally. Thus refurbishing or replacing such parts can help decrease the noise.



Conclusion:

Car engine sounds are normal.However any different sound observed may be a symptom of engine malfunctioning.Thus it is highly recommended that any such abnormality should be immediately reported and serviced soon in order to maintain the engine in good shape.


Frequently Asked Questions: Car Engine Sound.


1.Why is a squeaking sound coming from my car engine?

The most common reason for a squeaking sound coming from a car engine is due wear and tear of the belt drive.It can be addressed by applying a belt dressing or replacing the belt.

2.Is knocking which is observed in the car engine bad ?

Yes.The presence of engine knock is an indication that the combustion is not happening properly in the cylinder.


3. What is the best course of action if I observe an abnormal engine sound?



Engine noise is something that should not be taken lightly.It is an indication of a malfunction which can become costly if not nipped in the bud.Getting your engine checked by an authorised mechanic is the way to go.

Citations:


Priede, T., “Problems and Developments in Automotive Engine Noise Research,” SAE Technical Paper 790205, 1979, https://doi.org/10.4271/790205.

Austen, A. and Priede, T., “Noise of Automotive Diesel Engines: Its Causes and Reduction,” SAE Technical Paper 650165, 1965, https://doi.org/10.4271/650165.

Russell, M., “Automotive Diesel Engine Noise and Its Control,” SAE Technical Paper 730243, 1973, https://doi.org/10.4271/730243.

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