Generac Power Systems OHVI GSH 190, Service Manual

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SeCTIoN 12: PISToN, rINGS & CoNNeCTING rod INSPeCTIoN & ASSeMblY
Figure 12-6. Match Marks on Rod and Cap
ASSeMblY ANd INSTAllATIoN
ASSEMBLY:
. Install the rings (Figure 2-).
a. Use a ring expander when installing rings into the piston
grooves.
b. Install the oil ring assembly first.
c. Install the second compression ring with its inside chamfer
facing up.
d. Finally, install the top compression ring.
2. Assemble piston, rod and wrist pin.
a. The assembly mark on piston must be toward the engine
flywheel side.
b. Coat the wrist pin, wrist pin bore in piston and the wrist
pin bore in rod with clean engine oil.
c. Install one snap ring into the piston's wrist pin bore.
NOTE: Use new snap rings when reassembling the
piston.
d. Assemble the piston to the connecting rod. The assembly
mark dimple on top of the piston should be opposite the
match marks on the rod. See Figure 2-7.
SNAP
RING
CONNECTING
ROD MATCH
MARKS
WRIST PIN
ASSEMBLY MARK
DIMPLE
Figure 12-7. Assemble Piston to Connecting Rod
e. Slide the wrist pin through the piston bore opposite the
side with the snap ring (installed in Step 2c), then through
the rod and the second piston bore until it contacts the
snap ring.
f. Finally, install the second snap ring to retain the wrist pin
in the piston and rod bores.
INSTALLATION:
. Coat the cylinder walls with clean engine oil.
2. Coat crankshaft crankpin, connecting rod bearing and
connecting rod cap bearing with engine oil.
. Reinstall the crankshaft.
. Stagger the ring end gaps so that they are 90° apart.
5. Use a ring compressor to compress the piston rings back into
their grooves in the piston. Rings must be fully compressed.
6. Guide the connecting rod into the cylinder carefully. The
assembly mark dimple on the piston must be toward the
flywheel side of engine ( o’clock position).
NOTE: The connecting rod has a large offset bearing
end, therefore it MUST be installed exactly the way in
which it was removed, with the match marks facing the
governor arm.
Figure 12-8. Match Marks on Rod Facing Governor Arm.
7. When the ring compressor contacts top of cylinder, use
a wood handle or rubber mallet to gently tap the piston
down into the cylinder.
8. Check that the connecting rod large diameter bearing is
coated with clean engine oil, as well as the crankpin and
connecting rod cap.
9. Guide the connecting rod large diameter bearing over the
crankshafts crankpin (rod journal).
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