Engine Component Description: Crankcase

The cylinder block is constructed of aluminum alloy by the precision sand casting method and is constructed of two sections, an upper and a lower crankcase, split at the crankshaft center line. The grey cast iron cylinder liners are cast with the upper crankcase. The upper and lower crankcase sections are held in alignment by four dowel pins. Once machined, the sections must be kept together as a set. Sealing between the crankcase halves consists of a silicone rubber seal and a bead of anaerobic sealant along each side. Since the lower crankcase contains the lower main bearings, this casting adds to the structural rigidity of the engine assembly. Both upper and lower crankcases incorporate oil drain back passages isolated from the crankcase. These passages provide a direct path from the cylinder heads to the oil pan in order to prevent the needless aeration of the oil through contact with the rotating components. An oil gallery through the block supplies four oil jet assemblies used to cool the cylinder pistons. The assembly is bolted between two cylinders and incorporates two jets. Each assembly contains a spring operated check valve to maintain proper oil pressure.