The image below is called a cylinder liner or a cylinder sleeve. This auto part is inserted into the engine block. In other engines, there are no cylinder liner or cylinder sleeve, they only have cylinders directly part of the block.
The cylinder liner is where the piston goes up and down for intake and exhaust system. This is directly lubricated by the engine oil. In order for the oil not to be mixed with the fuel, a piston ring is needed to seal the space between the piston and cylinder liner or cylinder sleeve for better compression and avoid overheating in the engine.
When the piston ring or the cylinder liner is perforated oil will be pushed up into the fuel chamber and it will be mixed making a bluish smoke emitted by the engine.
In many cases, if signs are obvious there is a need for the piston rings to be replaced for proper engine oil sealing.
However, if the cylinder liner has already scratches which the piston rings cannot seal, the cylinder liner has to be replaced, it can be oversized from the standard measurement to 0.25mm or to 0.50mm.
If cylinder or cylinder liner is necessary for oversizing piston and piston rings should also be replaced with 0.25mm to 0.50mm.
However, others opt not to replace the piston but only the piston rings for practicality reason. If your car is not for racing they don’t advice you to replace the piston but only the piston rings.
Oversizing the cylinder liner, piston and piston rings has started with the myth of having a larger size other than the normal one is stronger and faster you can take advantage of.
So make a choice if you are the owner of the car. If you are in a race and you believe on the myth of oversized cylinder liner then you do. Because this will surely be the advice of the persons who work in the Machine Shops.
However, if you use your car for family services and necessities you may just have the piston rings to be replaced with an oversized one.
The Issue on this Cylinder Sleeve
As you can see on the above image of the cylinder which is about to be oversized, there is a lining around near to the top. You don’t see a crack but a color pencil like. The serviceman decided not to continue oversizing it until the owner decides for it.
The oversizing is to 0.50mm because of deep scratches made by an unknown cause. For sure even you replace the piston ring it cannot seal the engine oil to go up and be mixed with the fuel.
The mark is far above where the piston ring can reach. It’s a part of the combustion chamber.
Find related issues here on bluish smoke.
Thank you for reading. I hope it helped you. Please drop a comment below and I’ll get back to you as soon as I read it.