10.11
Section 10
Inspection and Reconditioning
10
Install Piston Rings
To install piston rings, proceed as follows:
NOTE: Rings must be installed correctly. Ring
installation instructions are usually included
with new ring sets. Follow instructions
carefully. Use a piston ring expander to install
rings (see Figure 10-10). Install the bottom
(oil control) ring first and the top compression
ring last. Refer to Figure 10-11.
1. Oil Control Ring (Bottom Groove): Install the
expander and then the rails. Make sure the ends
of expander are not overlapped.
2. Second Compression Ring (Center Groove):
Install the center ring using a piston ring
installation tool. Make sure the "pip" mark is up.
3. First Compression Ring (Top Groove): Install the
top ring using a piston ring installation tool. If no
"identification" mark exists to denote "up" the ring
is symmetrical and may be installed with either
side up.
Connecting Rods
Offset Stepped-Cap Connecting Rods are used in all
these engines.
Inspection and Service
Check bearing area (big end) for excessive wear,
score marks, running and side clearances (refer to
Section 1, ‘‘Specifications, Tolerances, and Special
Torque Values’’). Replace rod and cap if scored or
excessively worn.
Service replacement connecting rods are available in
STD crankpin size and 0.25 mm (0.010 in.) undersize.
The undersized rod is marked US .25 mm with purple
ink on the rod shank. Always refer to the appropriate
parts information to ensure that correct replacements
are used.
Closure Plate Assembly
Inspection
Inspect the oil seal in the closure plate and remove it if
it is worn or damaged. The new oil seal is installed
after the closure plate is assembled to the crankcase.
See ‘‘Install Closure Plate Oil Seal’’ in Section 11.
Inspect main bearing* (if so equipped) for wear or
damage (refer to Section 1, ‘‘Specifications,
Tolerances, and Special Torque Values’’). Replace
closure plate assembly if required.
Governor Assembly (Internal)
Inspection
Inspect the governor gear teeth. Replace the gear if it
is worn, chipped, or if any teeth are missing.
Inspect the governor weights. They should move freely
in the governor gear.
Figure 10-10. Installing Piston Rings With Expander.
Figure 10-11. Piston Ring Installation.
Piston Ring
End Gap
"Identification
"Mark
Piston
Top Compression
Ring
Center Compression
Ring
Rails
Expander
Oil Control Ring
(Three-piece)
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