16-5 To inspect

Cylinder bore, engine types AR and AS

To inspect 16-5

To ensure the best performance during the life of the engine it is important that worn or damaged cylinder bores are corrected. The condition of a cylinder bore is decided by: ! The amount and location of any polished areas. ! Wear. ! Damage to the cylinder wall. Note: It will not be necessary to correct the bore if: ! The honed finish can still be clearly seen. ! The engine performance and oil consumption is acceptable. 1 Inspect the surface of the cylinder bore for cracks and deep scratches. 2 Check the bore wall for areas where the honed finish has been polished away. Check especially the area around the top of the liner bore just below the carbon ring. In this area, thrust from the top piston ring is at its maximum.

Cautions:

! Do not use "Flex-hone" to repair cylinder bores. ! An engine can have high oil consumption with very little wear of the cylinder bores, if the surfaces of the bores are glazed. ! Specialist training and equipment is needed to machine the finish of a cylinder bore. If necessary, the cylinder bores can be bored and honed 0,50 mm (0.0197 in) and 1,00 mm (0.0394 in) oversize in diameter and oversize pistons fitted. To obtain oversize cylinder bores they must be bored and then diamond honed, silicon carbide base honed and silicon carbide plateau honed to the finished size to conform to the dimensions in the data and dimensions at the end of this section. Specialist training and equipment is needed to machine a cylinder bore. For further information contact your nearest Perkins distributor.