surface the piston sleeve is also heated to a normal working temperature the compression force and the force due to thermal expansion deforms the piston sleeve and changes the non cylindrical bore into a substantially cylindrical bore application_number US 52011100 A description a piston sleeve 10 for an internal combustion engine 12 is a tubular member with an axis 14 the sleeve 10 has a top surface 16 a bottom surface 18 a radially inner surface 20 and an outer surface 22 the top surface 16 is in a plane that is perpendicular to the axis 14 the bottom surface 18 is also in a plane that is perpendicular to the axis 14 the top surface 16 is separated from a surface 24 on the cylinder head 26 by a gasket 25 normally the block top surface 28 of the engine block 30 is perpendicular to the axis 14 of the piston sleeve 10 it is convenient to have the sleeve top surface 16 in a plane that is parallel to the top surface 28 of the engine block 30 by placing the top surface 16 of the piston sleeve 10 in a plane that is perpendicular to the axis 14 force exerted on the sleeve by the cylinder head 26 is exerted in a direction that is parallel to the axis 14 there.