Breather Operation
The crankcase is ventilated through an opening
in
the top
(magneto) side of the block. The opening is under the
flywheel and connects to a passage with a sheet metal
cover that in turn ventilates to the breather in the side of
the engine.
The breather uses a valve
to
prevent air entering the
crankcase when the piston is moving toward
TDC.
The
valve allows pressure to escape, or vent back to the clean
side of the air cleaner when the piston
is
moving toward
BDC.
Ventilation to the air cleaner occurs through a tube
that connects the breather to the air cleaner body. Any oil
that collects
in
the bottom of the breather will drain back to
the sump through a small drilled passage in the bottom of
the breather cavity in the block.
Breather Removal
-..
Figure
61
2.
Remove the
two
3/8"
hex, washer head cap screws
that retain the breather assembly in the side of the
engine.
Oil
Pump Operation
The GTS
150
uses a gerotor style, positive displacement
oil pump. The pump is driven by a cross pin in the end of
the cam shaft. Oil is drawn into the expanding cavities in
the gerotor pump set and issqueezed outthrough collaps-
ing cavities opposite the intake opening. Oil is discharged
through the center of the camshaft to a drilled passage
from the upper camshaft bearing to the upper crankshaft
bearing. The oil is then discharged through another drilled
passage in the bottom
of
the upper main bearing. From
there the oil splashes down over the rest of the engine
components.
Engine
36
The counterweight and connecting rod throw oil to
a
passage that leads to the head assembly. There is
a
hole
in the sump side of the engine that allows oil to drain back
from the head.
Oil Pump Removal
1.
Turn the engine over and remove the three
3/8"
hex,
flange head cap screws that retain the oil pump cover.
See Figure
62.
2.
Use a magnet to remove the gerotor set. The toler-
ances of these parts do not require that they be kept in
the same relationship for assembly. See Figure
63.
-,
-
-
SET
Figure
63
Sump Removal
1.
Remove the seven
3/8"
hex, washer head cap screws
that retain the sump to the block of the engine. See
Figure
64.
Figure
64
GTS
150
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