Modern liners employ bore cooling at the top of the liner where the pressure stress is high and therefore the liner wall thickness has to be increased. This brings the cooling water close to the liner surface to keep the liner wall temperature within acceptable limits so that there is not a breakdown in lubrication or excessive thermal stressing. Although the liner is splash lubricated from the revolving crankshaft, cylinder lubricators may be provided on the larger engines.

On the example shown opposite, the lubricator drillings are bored from the bottom of the liner circumferentially around the liner wall. Another set of holes are drilled to meet up with these vertically bored holes at the point where the oil is required at the liner surface.

Other engines may utilise axial drillings as in a two stroke engine.

Sulzer ZA40 Liner (vee engine; The straight engine is similar)

MAN-B&W L58/64 Liner

Where the cooling water space is formed between the engine frame and the jacket, there is a danger that water could leak down and contaminate the crankcase if the sealing O rings were to fail. As a warning, "tell tale" holes are led from between the O rings to the outside of the engine.

modern engines tend not to use this space for cooling water. Instead a separate water jacket is mounted above the cylinder frame. This stops any risk of leakage of water from the cooling space into the crankcase (or oil into the cooling water space), and provides the cooling at the hottest part of the cylinder liner.

Note that the liner opposite is fitted with a fireband. This is sometimes known as an antipolishing ring. It is slightly smaller in diameter than the liner, and its purpose is to remove the carbon which builds up on the piston above the top ring. If this carbon is allowed to build up it will eventually rub against the liner wall, polishing it and destroying its oil retention properties.