In what situation would a mechanic want to degrease cylinders?

Degreasing cylinders is an important step when preparing to install new pistons and rings. This process helps ensure that the surfaces are clean and free from oil, dirt, or other contaminants that could interfere with the proper seating and function of the new components. A clean cylinder allows for better sealing between the piston rings and the cylinder walls, which is critical for maintaining proper compression and engine efficiency.

In preparation for installing pistons and rings, removing any old oil residue or carbon build-up from the cylinder walls also aids in achieving an optimal fit between the new pistons and the cylinder. This can help prevent premature wear and potential engine damage, ensuring a smoother operation once the engine is reassembled and running.

Other options may involve tasks that do not necessarily require degreasing the cylinders. For instance, painting engine components or rebuilding a carburetor typically does not impact the cylinder's cleanliness in relation to piston and ring installation. Similarly, checking oil pressure focuses on the lubrication system rather than the condition of the cylinder itself.