Engine Lubrication: Description and Operation

The engine uses a gerotor type lubricating pump. The machined cavity in the block is the same for all engines. The pressure regulating valve is designed to keep the lubricating oil pressure from exceeding 449 kPa (65 PSI). When the lubricating oil pressure from the pump is greater the 499 kPa (65 PSI), The valve opens uncovering the dump port so part of the lubricating oil is routed to the oil pan. Because of manufacturing tolerances of the components and the oil passages, the lubricating oil pressure can differ as much as 69 kPa (10 PSI) between engines.

The engines use full flow, plate type oil coolers. The oil flows through a cast passage in the cooler cover and through the element where it is cooled by the engine coolant flowing past the plates of the elements. After the oil is cooled, it flows through the full flow oil filter.

The lubricating oil cooler cover contains a bypass valve the will let the lubricating oil flow bypass a plugged filter. The valve is designed to open when the pressure drop across the filter is more than 172 kPa (25 PSI), as with a plugged filter and lets the lubricating oil continue on through the engine. When a filter becomes plugged, an oil pressure decrease of 60 kPa (10 PSI) or less from normal operating pressure can be observed on the vehicle lubricating oil pressure gauge. This allows unfiltered oil into the engine. This condition should be avoided by changing the filter at each oil change.

The turbocharger receives filtered, cooled and pressurized lubricating oil through a supply line from the filter head. A drain line connected to the bottom of the turbocharger housing returns the lubricating oil to the lubricating oil pan through a fitting in the cylinder block.

The main bearings and the valve train are lubricated by pressurized oil directly from the main oil gallery. the other power components, connecting rods, pistons, and camshaft receive pressurized oil directly from the main oil gallery. Passages in the crankshaft supply oil to the connecting rods bearings. The oil is supplied to the camshaft journals through passages in the main bearings saddles. Smaller passages in the main bearings saddles supply oil to the pistons cooling nozzles. The spray from the nozzles also provides lubrication for the piston pins.

Lubrication for the valve train is supplied through separate passages in the cylinder block. Oil flows through the passages and across the oil transfer slot in the cylinder head gasket. From the transfer slot, the oil flows around the outside diameter at the cylinder capscrew, across a slot in the bottom of the rocker lever support, and up the vertical passage in the support. From these passages, oil flows through passages in the rocker lever shaft to lubricate the rocker levers. The oil from the channel lubricates the valves stems, push rods, and tappets.