Crankshaft; Inspecting The Oil Clearance; Installing The Crankshaft - Westerbeke 12C-TWO Operator's Manual

CRANKSHAFT
INSPECTING THE CRANKSHAFT
To check the crankpins and main journals for tapering and
out-of-round wear, the diameter of each crankpin or main
journal should be measured at two places along the crankpin
or main journal, in two directions "A" and "B" each place. If
necessary, regrind the crankpins and main journals to the
next undersize. If any crankpin or main journal has been
worn beyond the service limit, replace the crankshaft.
INSPECTING THE CRANKSHAFT OIL CLEARANCE
Oil clearance is calculated by subtracting the diameter of the
main journal or crankpin from the inside diameter of the
main bearing or rod bearing. To check the main bearings and
rod bearings for tapering wear and out-of-round wear, the
inside diameter of each main bearing or rod bearing should
be measured. After its bearing cap is fastened at the specified
torque, measure the bearing at two places along the length of
the bearing and in the directions "A" and "B" each place as
shown. If necessary, replace the worn bearing with a new
one. If the oil clearance still exceeds the service limit, regrind
the crankshaft to the next undersize and replace the bearing
with one of the corresponding undersize.
Direction of
installation of cap.
Bearing tightening
torque: (36 - 38 ft-lb)
(5.0- 5.5
m-kg)
FRONT
¢:=
Crankshaft end play;
0.002 - 0.007 in
(0.05- 0.175
mm)
19
®[]
MEASURING MAIN BEARING J.D.
NOTE:
A crankshaft which has been sized cannot be reground
to any undersize.
Main Journal Diameter
Standard 1.693in (43mm)
Limit -o.0275in (-D.7Dmm)
Crankpin Diameter
Standard 1.575in (4Dmm)
Limit -o.0275in (-0.7Dmm)
Main Journal Undersize Diameter
0.25 US 30.885- 30.896in (42.715- 42.73Dmm)
.50 US 30.704- 30.715in (42.465 • 42.48Dmm)
Crankpin Undersize Diameter
0.25 US 28.715 • 28.727in (39.715- 39.73Dmm)
0.50 US 28.535 • 28.5461n (39.465 • 39.48Dmm)
Oil Clearance Service LimH
Main Bearing D.OD4in (0.1Dmm)
Rod Bearing O.OD6in (0.15mm)
Tightening Torque
Main Bearing 36 • 38 ft·lb (5.0 - 5.5m-k)
Rod Bearing Cap Nut 23 - 35 ft-lb (3.2 • 3.5m-k)
Crankshaft End Play 0.002- D.DD7in (0.05- 0.175mm)
INSTALLING THE CRANKSHAFT
Refer to the callouts in the illustration below.
ThrUst bearing only
for No. 2 cap. :
~-•
bS/desealscoated
' with sealant
• (Three Bond 1212).
\ J: _.-. . . . . . . .
\j~
Make cap /lush with
cylinder block end face
(common to front and
rear end faces).
INSTAWNG THE CRANKSHAFT