Engine Component Description (LF4): Crankcase

The cylinder block is unique to the LF4 due to the need for specific turbocharger oil and coolant connections and PCV flow, and is constructed of aluminum alloy by precision sand-casting with cast in place iron cylinder liners. Each nodular main bearing cap incorporates 6 bolts bolting the cap into the engine block. Along with 2 outer and 2 inner bolts, 2 side bolts are used in the deep skirt block. To prevent aeration, oil return from the valvetrain and cylinder heads is channeled away from the rotating and reciprocating components through oil drain back passages incorporated into the cylinder heads and engine block. Pressure-actuated piston oil cooling jets are mounted between opposing cylinders. Twin knock sensors are located in the valley of the block between the cylinder heads. The knock sensors have an acoustic foam noise barrier that surrounds them in the valley. The crankshaft position sensor is located on the right side of the exterior of the engine block under a sheet metal heat shield to protect it from turbocharger heat.