TM 5-3805-258-24-1ENGINELUBRICATION SYSTEMhas an orifice to restrict the oil flow to the rockerarms. The rear rocker arm bracket also has an O-ringthat seals against the head bolt. This seal prevents oilfrom going down around the head bolt and leakingpast the head gasket or spacer plate gasket. The O-ring must be replaced each time the head bolt isremoved from the rear rocker arm bracket.Holes in the rocker arm shafts let the oil givelubrication to the valve system components in thecylinder head.After the lubrication oil has done its work, it goesback to the engine oil pan.There is a bypass valve in the oil pump. Thisbypass valve controls the pressure of the oil comingfrom the oil pump. The oil pump can put more oil intothe system than is needed. When there is more oilthan needed, the oil pressure increases and the by-pass valve will open. This allows the oil that is notneeded to go back to the engine oil pan.With the engine cold (starting conditions), bypassvalves (9 and 10) will open and give immediate lubri-cation to all components when cold oil with highviscosity causes a restriction to the oil flow throughoil cooler (15) and oil filter (11). Oil pump (13) sendsthe cold oil through the bypass valves around the oilcooler and oil filter to oil manifold (5) in the cylinderblock.When the oil gets warm, the pressure difference inthe bypass valves decreases and the bypass valvesclose. Now there is a normal flow of oil through theoil cooler and oil filter.SYSTEMS OPERATIONThe bypass valves will also open when there is arestriction in the oil cooler or oil filter. This actiondoes not let an oil cooler or oil filter with a restrictionprevent lubrication of the engine.ROCKER ARM OIL SUPPLYFLOWOF OIL (ENGINECOLD)9. Oil cooler bypeee. 10. Oil filterbypasa. 11. Oil filter. 12. Turbocharger. 13. Oil pump. 14. Oil pan. 15. Engine oil cooler.3-14
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