One of the major problem of a car engine is a knock. When this happens, your engine with smooth running sound begins to tap as you accelerate your car vehicle.

This is an obvious sign of “engine knock” but there is more to it than a tapping sound. Car Knocks are caused by a variety of individual errors in the car engine which also comes with it’s unique sound. Getting to know the origin of the knocking sound on the car can be tricky, however, these are the major five (5) causes of car Knocks.

Low Octane

When your car engine is smooth and sound in operation, air/fuel ratio gradually burns in a single detonating compartment of a cylinder. When this happens in more than one location per time, a detonating knock sound is given out. This is because the Air/fuel ratio ignite and collide with each other before the schedule time.

So, if your car Octane ratio is high with respect to it’s performance, try and maintain that standard by going for fuel with high Octane rating. This will ensure uniformity and fight engine knocks.

Fuel and lean air mixture

This is caused by issues with fuel pump, oxygen sensors and air sensors. When this happens, the car system lacks fuel but has excess of air. Ultimately, knocking sound will pop out when fuel is not enough to boost the mixture reaction.

Rod knock

When your car is in motion, it’s piston travels to and fro in the engine, this motion will rotate the crankshaft which powers the wheels. However, when the rod bearing (which is responsible for the bearing smooth movement) worns out, this causes knock sound. 

The solution requires new bearing and work on the crankshaft and piston.

Bad timing

When your engine accelerates, the spark plugs will fire. If it’s fires irregulary or abnormally, a Knock sound will be heard.

Failing knock sensor

When your knock sensor – a tool made to report knock sounds to the engine control unit fails to perform, this will produce knocks. Always check it as it is part of car diagnostic test. 

Note: it is not common in modern cars since timing and Air/fuel ratio is automatically controlled.