Engine knocking is among the problems usually encountered in the internal combustion engines though few factor can be said to cause such incident such as overheating in the engine, but the overheating has its root causes which can contribute to such overheating and other problems are what we shall be discussing in this post.
The engines use in automobiles have little difference in their cooling system when compared to common internal combustion engines use in domestic and small industrial purposes such the generators, and grinder movers, etc. the difference in the cooling system is that the automobile types has radiator and pumping system to circulate the water in the cooling system, while the later has no such mechanism.
Though the major part in the engine that creates engine knock is primarily the piston and its rings due to the expansion in the combustion chamber caused the high operating temperature of the engine.
Below are some possible causes of engine knocking when taken from their root;
Engine oil has lots of purposes in the engine which cooling is among, when the engine oil is low it increases the friction in the engine which leads to heat and wearing of parts in dynamic arrangement in the engine. The insufficiency of the lubricating oil in the engine will create serious problem to the engine which may be gradual but will lead to the knock down of the engine, one of the signs of insufficient oil in the engine is the change in sound and higher operating temperature. Since the chief causes of engine knocking is the expansion of the piston and piston rings in the combustion chamber due to overheating.
The increase in the temperature contributed due to insufficient oil adds to the overall engine operating temperature making the possibility of overheating to be higher.
DAMAGED PUMPING MECHANISM
For the internal combustion engines where water and oil pumping mechanisms were built in them, the damage to any of the mechanism may not be noted quickly except when a detecting means is included in the engine, but when there is exception to that; their damage could cause a sudden rise in the engine operating temperature and leads to the piston and rings expansion which causes engine knocking.
LOW WATER GAUGE
Another possible factor could be low water gauge, when the water in circulation in the parts of the engine had gone low due to evaporation or leakage it will contribute to the engine knocking by causing rise in the engine temperature.
BAD PISTON RINGS
Another cause of this problem could be bad piston rings which could be either made with wrong material or may be a good one but was wrongly fixed to the piston. If the latter is the case then other factors in the engine may be in their normal condition, even the engine may not be having overheating, while the intense speed of the engine could cause the wrongly fixed piston rings to break and block the clearance between it and the combustion cylinder.
When considering the manufacturing of piston the major property of materials under considerations are, low expansion, low malleability, strong hardness, low thermal conductivity and lighter weight, for this reason pistons were made with alloy of aluminum and magnesium to be able in meeting these required properties, but when the wrong metal alloy is used in the manufacturing of the piston, it leads to easy expansion of the piston which in turn forces the rings to block the reciprocating movement in the combustion chamber.
These were the list of known possible causes of engine knocking, but in the case of personal experience concerning this post, the comment box is open for your contribution and responses to others contribution.