4.3L Vortec 6 cylinder oil and lubrication system
Full pressure lubrication, through a full-flow oil filter is supplied by a gear-type oil
pump. Oil is drawn up through the oil pump screen and passes through the pump to
the oil filter. The oil filter is a full-flow paper element unit with an anti-drain back
valve. An oil filter bypass valve is used to ensure adequate oil supply, in the event
the filter becomes plugged or develops excessive pressure drop. Filtered oil flows
into the main gallery and then to the camshaft, the balance shaft, the rear bearing,
and the crankshaft bearings.







The valve lifter oil gallery supplies oil to the valve lifters. Oil flows from the valve
lifters through the hollow valve pushrods to the valve rocker arms. Oil drains back to
the crankcase through the oil drain holes in the cylinder head. The camshaft timing
chain is drip fed from the front camshaft bearing. The pistons and piston pins are
lubricated by oil splash.