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| Illustration 1 | g00849191 |
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(1) Reduced pressure passages
(2) Splash and drain (3) Plate type oil cooler (if equipped) (4) High pressure passages (5) Cooling lines for water (6) Engine oil pump (7) Suction side (8) Engine oil filter (9) Canister type oil cooler (if equipped) | |
Pressure for the lubrication system is supplied by engine oil pump (6) which uses rotors. The engine oil pump is driven by an idler gear. The crankshaft gear drives the idler gear. The engine oil pump has an inner rotor and an outer rotor. The axis of rotation of the rotors are off-center relative to each other. There is a key between the inner rotor and the drive shaft. If a balancer unit is equipped on four cylinder engines, the engine oil pump is installed in the balancer frame. The engine oil pump is driven by the drive shaft in the balancer unit.
The inner rotor has six lobes which mesh with the seven lobes of the outer rotor on four cylinder engines. Six cylinder engines have four inner lobes and five outer lobes in the engine oil pump. When the pump rotates, the distance increases between the lobes of the outer rotor and the lobes of the inner rotor in order to create suction. When the distance decreases between the lobes, pressure is created.
Lubricating oil from the oil pan flows through a strainer and a pipe to the suction side (7) of the engine oil pump. On four cylinder engines, the lubricating oil flows from the outlet side of the pump through a pipe to a relief valve. From the relief valve, lubricating oil passes to a plate type oil cooler (if equipped). On six cylinder engines, the lubricating oil flows from the outlet side of the pump through a pipe and a passage to the filter head. The oil then flows from the filter head through a pipe to a plate type oil cooler (3). The oil cooler is typically located on the left side of the engine.
On four cylinder engines, the plate type oil cooler has seven plates on the left side of the engine or the oil cooler can be a canister type oil cooler (9) with ten plates. For six cylinder engines, the plate type oil cooler that is used on naturally aspirated engines has four plates and the oil cooler that is used on turbocharged engines has eight plates. Some oil coolers are equipped with a bypass valve. Cold oil can create a restriction to the flow of oil in the oil cooler. When this happens, the bypass valve opens allowing the oil to flow directly from the inlet side to the outlet side of the cooler.
On four cylinder engines, lubricating oil from the oil cooler passes to the oil filter. On six cylinder engines, lubricating oil from the oil cooler returns through a pipe to the filter head. The oil divides between the relief valve and the oil filter.
The oil flows from the oil filter through a passage that is drilled across the cylinder block to the oil gallery. The oil gallery is drilled through the total length of the left side of the cylinder block. If the oil filter is on the right side of the engine, the oil flows through a passage that is drilled across the cylinder block to the pressure gallery.
Lubricating oil from the oil gallery flows through high pressure passages (4) to the main bearings of the crankshaft. The oil then flows through passages in the crankshaft to the large end bearings of the connecting rod. The pistons and the cylinder bores are lubricated by the splash and the mist of the oil.
Lubricating oil from the main bearings flows through high pressure passages (4) in the cylinder block to the journals of the camshaft. The oil flows from the second journal of the camshaft at a reduced pressure. The oil flows through a passage in the cylinder block to the cylinder head. The oil then flows into the rocker arm shaft at a reduced pressure (1) to the bearings of the rocker arm levers. The valve stems, the valve springs and the valve lifters are lubricated by the splash and the mist of the oil.
The hub of the idler gear is lubricated by oil from the oil gallery. The timing gears are lubricated by the splash of the oil.
The turbocharger (if equipped) is lubricated by oil from the oil filter through the engine block. An external line from the engine block supplies oil to the turbocharger. The oil passes through the turbocharger and returns through a line to the oil pan.
Piston cooling jets (if equipped) are connected to the oil gallery. The piston cooling jets spray lubricating oil on the underside of the pistons in order to cool the pistons.