Polaris TRAIL BOSS 325 2001, Manual

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ENGINE
3.9
OIL FLOW -- ES32PF
The ES32PF engine is equipped with a thermostatically controlled valve that directs oil returning to the engine
through a cooler when the oil is hot. Valve operation is described below. The chart on page 3.10 describes the
flow of oil through the ES32PF engine and oil cooler. Beginning at the engine sump, the oil flows through a screen
in the bottom of the crankcase into the feed side of the oil pump. Oil then passes through the crankcase oil pas-
sage to the inlet hose, and on to the oil cooler thermo valve. The thermo valve directs oil back to the crankcase
if oil temperature is low. If oil temperature is hot, the thermo valve directs oil through the oil cooler first, and then
back to the crankcase. After passing through the crankcase passage, oil is pumped through to the oil filter. If the
oil filter is obstructed, a bypass valve contained in the filter allows oil to bypass the filter element.
At this point, the oil is diverted in two directions. Oil is supplied to the camshaft through the right front cylinder
head bolt passage and into the camshaft through the camshaft journal. The camshaft journals, cam lobes, and
rocker arms are lubricated through holes in the camshaft. Splashed oil lubricates the cam chain, sprocket, and
valve springs, and drains to the sump.
The other oil path from the filter leads to the crankcase main oil passage, which leads to the crankshaft. An oil
seal on the stator plate prevents oil from entering the stator/flywheel area. Oil travels through the crankshaft to
the crank pin, lubricating the connecting rod large end bearing directly. Oil also passes through an oil jet (drilled
orifice) in the end of the crank pin to the PTO end main bearings.
Residual oil from the lubrication of the crankshaft and connecting rod indirectly lubricates the cylinder wall, piston,
rings, connecting rod small end bearing, piston pin, cam chain drive sprocket, and Magneto end crankshaft main
bearing.
NOTE: The oil lines and clamps are designed for high pressure. DO NOT SUBSTITUTE. Use genuine Polaris
oil lines and clamps.
Oil Cooler Mounted Thermo Valve