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 would 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 are unaware of. Engine knocking refers to the metallic sound while applying pressure on the gas pedal. The sound could be hollow knocking kind or rattling in either ways you would want to keep the engine smooth and less noisy.
How to identify if your engine is 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 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 such as it releases nitrogen oxide and unburned hydrocarbons, which are poisonous gases that can cause asthma and emphysema. So you need to get 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 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.
Engine knocking cannot be easily recognized, and one needs to have some knowledge if not ample about the technicalities of the vehicle to resolve the problem. And when you identify the problem it is not really necessary for you dismantle the entire engine instead try to find the root cause of the knock and then try to rectify it without actually removing the engine.
How can you prevent or avoid engine knocking?
- Using appropriate octane-reading 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 for reasons unknown to us and thus cannot be avoided.
- Do not go on long rides without breaks; engines that become overheated tend to knock off.
Article Idea & Inspiration From: The Bike Chronicles of India
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{ 3 comments… read them below or add one }
thanks for the wonderful post.
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.
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