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
Specications). 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.
Undersized rods have an identication marking on 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 Detail
A Self-Tapping Screw B Flat Washer
C Plug D Crankshaft
A
B
C
D
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 insure
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.
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. Measure running clearance between
crankshaft journals and their respective bearing bores.
Use an inside micrometer or telescoping gauge to
measure inside diameter of both bearing bores in vertical
and horizontal planes. Use an outside micrometer
to measure outside diameter of crankshaft main
bearing journals. Subtract journal diameters from their
respective bore diameters to get running clearances.
Check results against tolerances in Specications. If
running clearances are within specication, and there
is no evidence of scoring, grooving, etc., no further
reconditioning is necessary. If bearing surfaces are worn
or damaged, crankcase and/or oil pan will need to be
replaced.
Inspect crankshaft keyways. If 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 Specications
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 1 size under.
When grinding 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 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.
Remove Flywheel End Oil Seal
Remove oil seal from crankcase.
Disassembly/Inspection and Service
72
24 690 07 Rev. HKohlerEngines.com
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