Westerbeke 8.0KW-60Hz Service Manual page 28

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ENGINE INSPECTION
13.
Idler gear.
a. Measure the bore in the idler gear for the shaft and the
diameter of the shaft to find the clearance. If the
clearance exceeds the limit, replace the gear or shaft
whichever is badly worn. .
CLEARANCE BETWEEN THE IDLER GEAR AND THE SHAFT
STANDARD 0.0012' 0.0028 In (0.03 • 0.07mm)
LIMIT 0.0079 In (0.20mm)
b. Install a'new idler shaft to the cylinder block so that its
dimension from the face of the block is 1.043 ± 0.020 in
(26.5 ± O.Smm).
DIMENSION OF THE
IDLER SHAFT FROM
THE BLOCK FACE
14. J!1ywheel
mid
ring gear
a. Put the flywheel on the surface plate. Set a dial
indicator at one side of the friction (clutch contact) face
and move it over to the opposite side of the face .s
shown in the illustration to find fiatness. If fiatness
exceeds the limit, grind the face~
. FLATNESS OF THE FLYWHEEL
STANDARD 0.0059 in (0.15mm) MAXIMUM
LIMIT 0.0197 in (0.50mm)
MEASURING FLYWHEEL
FLATNESS
b. Check the ring gear and replace it if its teeth are
abnormally worn or chipped.
(1) Removal
Heat the ring gear evenly with an acetylene torch.
Tap the ring gear all
the
way around with a bar and
• hammer as shown in the illustration to remove it
from the flywheel.
(2) Installation ' . . ..
Heat a new ring up to a temperature of 302"F
(150°C) with a piston heater and install ii to the
flywheel with its unchamfered side foremost.
REMOVING THE
RING GEAR
22
15. Pistons; piston rings and piston pins.
a. Measure the diameter of the piston at its skirt in a
direciion transverse to the piston pin with a micrometer
as shown in the illustration. If the diameter exceeds the
limit, replace the piston. Select a new piston so that the
difference between average weight of all pistons in one
engine does not exceed the standard.
DIAMETER OF PISTON STANDARD
STANDARD (NOMINAL SIZE 3.0681 ·3.0689 in
3.0709 In (78.00mm) (77.93 -77.95mm)
OVERSIZE 3.0719 - 3.0787 in
0.0098 in'(0.25mm) (78.18 -78.20mm)
(NOMINAL SIZE 3.0807in
78.25nim)
LIMIT
3.063 In
(71.80mm)
3.0728 in
(78.05mm)
OVERSIZE
. 3.0878 - 3.0886 in 3.0827 In
0.0197 In (0.50mm)
(NOMINAL SIZE 3.09051n
78.50mm)
(78.43 - 78.45mm) (78.30mm)
MAXIMUM PERMISSIBLE DIFFERENCE BETWEEN AVERAGE WEIGHT OF
ALL PISTONS IN ONE ENGINE, g(oz)
STANDARD 0.18 In (5ml1\)
MEASURING
PISTON
DIAMETER
MEASURING
DIRECTION
h. Measure the clearance between the groove and piston
with a strrught edge and a feeler gauge. If the clearance
exceeds
th~
limit, replace the ring.
COMPRESSION RING CLEARANCE STANDARD
NO.1 COMPRESSION 0.0024 - 0.0039 In
RING (0.06 - 0.10mm)
NO.2 COMPRESSION 0.0020 - 0.0035 in
RING (0.05· 0.9mm)
OIL RING 0.0012 - 0.0028 In
(0.03 - 0.07mm)
LIMIT
0.0118 In
(0.30mm)
0.0079 In
(0.20mm)
0.0079 In
(0.20mm)
c. If the clearance still exceeds the limit after new piston
. rings have been installed, replace the piston.
NO.1 RING
COMPRESSION RING
MEASURING THE CLEARANCE BETWEEN
THE PISTON
RIN~
AND GRDOVE