Mechanic Glossary

Dry Sleeve Cylinder Block

An engine block where the pressed-in cylinder sleeves make contact only with the block cylinder walls, not the engine coolant.

A dry sleeve cylinder block is an engine block design. When cylinder walls wear out or crack, mechanics can restore the block by pressing in steel cylinder liners (sleeves). In a dry sleeve design, the sleeve is pressed tight inside a fully machined cast-iron or aluminum cylinder bore. The outer wall of the sleeve sits flush against the block metal, which conducts the heat. The sleeve does not make contact with the liquid engine coolant passages.

Dry sleeves are stable because the surrounding block metal supports them. They cannot leak coolant into the crankcase like wet sleeves can. However, pressing them in requires high precision. If there is any tiny air gap between the sleeve and block wall, heat will build up, warping the cylinder and causing the piston to lock up.

Frequently Asked Questions

A dry sleeve fits inside a machined bore and contacts only metal. A wet sleeve makes direct contact with the liquid coolant, using rubber O-ring seals at the bottom to stop leaks. Wet sleeves are easier to replace but can leak coolant into the oil.
To repair a cylinder wall that has been deeply scored by a broken piston ring, or to restore an expensive block to factory dimensions when it has already been bored out to its maximum limit.
The cylinder is bored out, the block is heated, and the sleeve is chilled in dry ice to shrink it. It is then pressed into the bore. Once the temperatures normalize, the sleeve is bored and honed to match the pistons.
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