53
Disassembly/Inspection and Service
24 690 34 Rev. D
KohlerEngines.com
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
Speci
fi
cations). 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.
An 0.25 mm (0.010 in.) undersized rod can be identi
fi
ed
by a drilled hole located in lower end of rod shank.
Always refer to appropriate parts information to ensure
correct replacements are used.
Remove Crankshaft
Inspection and Service
Crankshaft Components and Details
A
B
C
D
A
Self-Tapping Screw
B
Flat Washer
C
Plug
D
Crankshaft
E
G
F
H
E
Fillet Must Blend Smoothly with Bearing Journal
Surface
F
High Point from Fillet Intersections
G
45° Minimum
H
This Fillet Area Must Be Completely Smooth
NOTE: If crankpin is reground, visually check to ensure
fi
llet blends smoothly with crankpin surface.
NOTE: To prevent repeat failures, camshaft and
crankshaft should always be replaced as a set.
Carefully pull crankshaft from crankcase. Note thrust
washers and shims if used.
Inspect gear teeth of crankshaft. If teeth are badly worn,
chipped, or some are missing, replacement of crankshaft
will be necessary.
Inspect crankshaft bearing surfaces for scoring,
grooving, etc. Some engines have bearing inserts in
crankshaft bore of closure plate and/or crankcase.
Do not replace bearings unless they show signs of
damage or are out of running clearance speci
fi
cations. If
crankshaft turns easily and noiselessly, and there is no
evidence of scoring, grooving, etc., on races or bearing
surfaces, bearings can be reused.
Inspect crankshaft keyways. If they are worn or chipped,
replacement of crankshaft will be necessary.
Inspect crankpin for score marks or metallic pickup.
Slight score marks can be cleaned with crocus cloth
soaked in oil. If wear limits, as stated in Speci
fi
cations
and Tolerances are exceeded, it will be necessary to
either replace crankshaft or regrind crankpin to 0.25 mm
(0.010 in.) undersize. If reground, a 0.25 mm (0.010 in.)
undersize connecting rod (big end) must then be used to
achieve proper running clearance. Measure crankpin for
size, taper, and out-of-round.
Connecting rod journal can be ground one size under.
When grinding a crankshaft, grinding stone deposits
can get caught in oil passages, which could cause
severe engine damage. Removing crankpin plug when
crankshaft is ground provides easy access for removing
any grinding deposits collected in oil passages.
Use following procedure to remove and replace plug.
Procedure to Remove Crankshaft Plug:
1. Drill a 3/16" hole through plug in crankshaft.
2. Thread a 3/4" or 1" long self-tapping screw with a
fl
at
washer into drilled hole. Flat washer must be large
enough to seat against shoulder of plug bore.
3. Tighten self-tapping screw until it draws plug out of
crankshaft.
Procedure to Install New Plug:
Use 1 single cylinder camshaft pin as a driver and tap
plug into plug bore until it seats at bottom of bore. Make
sure plug is tapped in evenly to prevent leakage.
