MerCruiser 13, Service Manual

Page: 121 / 348

ENGINES - 3A - 31 90-816462 2-695
Inspection and Replacement
IMPORTANT: Before you remove the connecting
rod cap, mark the side of the rod and cap with the
cylinder number to assure matched reassembly
of rod and cap.
1. Remove connecting rod cap and bearing.
2. Inspect bearing for evidence of wear or damage.
(Defective bearings should not be installed) Typi-
cal bearing failures are shown under ”General”.
3. Wipe bearings and crankshaft clean of oil.
4. Measure crankpin for out-of-round of taper with a
micrometer. If not within specifications, replace or
recondition crankshaft. If within specifications
and new bearing is to be installed, measure maxi-
mum diameter of crankpin to determine new
bearing size required.
5. If within specifications, measure new or used
bearing clearances with Plastigage or equivalent.
IMPORTANT: If bearing is fitted to out-of-round
crankpin, br sure to fit maximum diameter of
crankpin. If bearing is fitted to minimum diameter,
and crankpin is out-of-round .001 (0.025mm), in-
terference between bearing and crankpin will re-
sult in rapid bearing failure.
a. Place a piece of guaging plastic the full width
of crankpin (parallel to crankshaft).
b. Install bearing connecting rod and cap.
c. Place a piece of gauging plastic, the length of
the bearing (parallel to the crankshaft), on the
crankpin or bearing surface as shown. Posi-
tion the gauging plastic in the middle of the
bearing shell. (Bearings are eccentric and
false readings could occur if placed else-
where.)
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a
a - Gauging Plastic
d. Install the bearing in the connecting rod and
cap.
e. Install the bearing cap and evenly torque nuts
to 45 lb. ft. (61 N·m).
IMPORTANT: Do not turn the crankshaft with the
gauging plastic installed.
f. Remove the bearing cap and using the scale
on the gauging plastic envelope, measure the
gauging plastic width at the widest point as
shown.
72362