In this quick story, we discuss what is engine knocking, what is engine snatching, and a few ways you can avoid engine knocking in your bike…

In a general scenario if you put forth a question as to what engine knocking is, we could get a definition that more aptly describes engine snatching rather than knocking. The description could be something as follows – when you accelerate the bike at low speed without changing the gear then the engine behaves jerky, which results in ‘engine knocking’.

But this is snatching and not knocking that many of us may not be aware of. Engine knocking refers to the metallic sound while applying pressure on the gas pedal. The sound could be hollow knocking kind or rattling; either ways you would want to keep the engine smooth and less noisy.

How to identify if your engine is knocking

what is engine knocking

When there is weak knock of your engine it should not worry you as much. In fact, it does a little good to your engine by increasing the flame speed. However, a strong knocking if not addressed at the right time can lead to an almost irreparable damage.

And the strong knock can be recognized from the sound; as if the engine is rattling just like the same noise your engine would emit when you drive very slowly in top gear. It’s like the noise comes when it shouldn’t; you go at optimum speed at the gear.

The negatives of engine knocking

Engine knocking could pose many pollution issues; it releases nitrogen oxide and unburnt hydrocarbons, which are poisonous gases that can cause asthma and emphysema. So you need to be aware of certain facts about engine knocking to keep the environment and the vehicle safe.

Causes of engine knocking

One of the main reasons for engine knocking could be improper combustion process, which is a result of early combustion due to the carbon build-up in the combustion chamber, insufficient air/fuel mixture and if the ignition occurs too quickly.

The engine knocking could also be due to overheating of the engine, which again is a combustion issue. Lack of exhaust gas circulation or irregular gasoline octane also leads to engine knocking.

Damage in crankshaft bearings, a broken flywheel that connects the engine to the transmission, an overused water pump bearing, a loose timing belt, a faulty air conditioning compressor or an alternator with overused bearing can all result in engine knocking; rather they are internal mechanical faults that can cause the engine to create that knocking sound.

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Engine knocking cannot be easily recognized, and one needs to have some knowledge to resolve the problem. And when you identify the problem, it is not really necessary for you to dismantle the entire engine. Instead you can try to find the root cause of the knock and then try to rectify it without actually opening up the internal parts.

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How can you prevent or avoid engine knocking?

  • Using appropriate and recommended octane-reading, good quality petrol for the engine
  • Give a warm up to the engine before you vroom off, and do not stress the engine during cold winters before it gets warmed or primed.
  • Never go for turbochargers that aren’t prescribed for your engine
  • There will be engines which come with poor inherent design and they develop knock off.
  • Do not go on long rides without breaks; engines that become overheated tend to knock off.

Next Read: “Which Engine Oil Shall I Use?” – Engine Oil Explained in Very Simple Terms

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4 COMMENTS

  1. My pulsar180 ug4 used to knock a quite during mornings(before the third service or so, i dont remember). Now it has totally resolved, i now hear the bass exhaust note. I got it serviced in time(5 services done), used normal petrol, warmed engine a bit after first start regularly.

  2. The above mantioned is for a car? or 2 wheelers. How can some one solve my problem. 2 months back I changed original piston and new head for my old shogun. But there is a knocking which irretates me. Pl suggest how to rectify this noise.Also some one kindly suggest which 2 stroke 2T and engine oil should I use. Iam using Castrol.

    Thanks.

    Deepak

  3. Engine knocking in new engine is not a fault especially while applying overload or uphilling the vehicle. This knocking can be reduced by changing the gear down appropriately. This is the sign of a well fitted/ very properly seated piston and piston rings which has a long engine life. The only draw back is engine heats immediately. In old engine, the cause of knocking is due to various reasons and most of the case the sould assumed as ‘knocking’ in old engines is actually not the knocking sound but it is due to slipping of worn out bearings, excessive tear and wear of internal moving parts in the engine assembly, excessive tappit gap, very loosed timer chain etc. I had a two wheeler which was knocking from its delivery from the show room. When informed at company’s authorised workshop they told this is the fault of main bearings of the engine and replaced the same with free of cost. But the knocking sould was still there. Such type of engine knocking, if required, can be removed if the hole of the fuel injuction jet is increaded.

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