Polaris 2012 Sportsman Forest 500 International, Руководство по обслуживанию

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3.15
ENGINE
3
9923412 - 2012 Sportsman 400/500 and EFI Tractor Service Manual
© Copyright 2011 Polaris Sales Inc.
Oil Flow
The following chart describes the flow of oil through the 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 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.
Vent Hose
Oil Tank
Oil Filter
Oil feed to filter
From filter to
One way valve
crankshaft
Top fitting is oil
feed or intake
from bottom of tank
Bottom fitting is oil
exhaust or return
to tank
Internal passage to
camshaft (front left
head bolt)