Westerbeke 20B TWO Tehnical Manual page 54

Checking the crankshaft for wear.
To check the
crankpins and main journals for tapering wear 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, as shown in the figure at right. If
necessary, regrind the crankpins and main journals to
the next under size. If any crankpin or main journal
has been worn out beyond the service limit, replace
the crankshaft.
Diameter of crankpin and main journal
(mm)
Description
Standard Service limit
Main journal
43 -0.70
dia.
Crankpin dia. 40 -0.70
Inspection of the crankshaft oil clearance.
Oil
clearance is calculated by subtracting the diameter of
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 bear-
ing or rod bearing should be measured, after its
bearing cap is fastened to the specified torque, at two
places along the bearing, and in two directions
"A"
and
"B",
each place as shown in the figure at right. 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 under size and
replace the bearing with one of the corresponding
under sizes.
CAUTION
Checking Crankshaft for Wear
Under·size diameters (mm)
Description Main journal Crankpin
0.25 US 42.715""'42.730 39. 715""'39. 730
0.50 US 42.465""'42.480 39.465""'39.480
2
Measuring Main Bearing 1.0.
A crankshaft which has been sized cannot be reground to any under size.
Tightening torque
(kgm)
Oil clearance
(mm)
Description Standard Description Service limit
Main bearing cap bolt
5.0""'5.5
Main bearing
0.10
Rod bearing cap nut
3.2""'3.5
Rod bearing
O. 15
Westerbeke Engines
52