Oil Flow - Eh50Pl - Polaris Ranger 500 2x4 2007 Service Manual

ENGINE

Oil Flow - EH50PL

The chart on Page 3.14 describes the flow of oil through the
EH50PL engine. Beginning at the oil tank, the oil flows
through a screen fitting in the bottom of the tank and into the
oil supply hose. The feed side of the oil pump draws oil
through the hose and into the crankcase oil gallery, and then
pumps the oil through another passage to the one way valve.
When the engine is off, the one way valve closes to prevent oil
in the tank from draining into the crankcase. The oil is
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pumped through a delivery pipe 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 left front cylinder stud, and an oil
passage in the head. Oil enters the camshaft through the PTO
(L) journal. The camshaft journals, cam lobes, and rocker arms
are lubricated through holes in the camshaft. The oil lubricates
the cam chain and sprocket and drains to the sump.
The other oil path from the filter leads through a delivery pipe
to the crankcase main oil gallery, which leads to the stator plate
oil passage. Here it passes through the slotted friction bearing
(located in the stator plate) into 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 and counterbalancer
gears.
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, oil/water
pump drive gears, cam chain and drive sprocket, and Magneto
end crankshaft main bearing.
The one-way valve is located on the front left (PTO) side of the
crankcase. The valve prevents oil in the tank from draining into
the engine sump when the engine is off. The valve mechanism
consists of a plunger, return spring, guide plug, and sealing
washer. When the engine is running, oil pressure lifts the
plunger off the seat, allowing oil flow. When the engine is off,
spring pressure forces the plunger against the oil passage seat,
preventing oil flow from the tank to the sump. The one-way
valve requires very little maintenance. If engine oil drains into
the sump when the engine is off, inspect the valve sealing
surface for debris or damage. Inspect the return spring for
distortion or damage.
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