Jeep UNIVERSAL CJ-2A - Page 70

'Jeep' UNIVERSAL and 'Jeep' DISPATCHER
E
E-38. Crankshaft
The crankshaft is machined from a heat-treated
carbon steel forging and is carefully balanced both
dynamically and statically. The crankshaft is
supported by three replaceable main bearings. The
front main bearing is flanged to take the end
thrust of the crankshaft. A flanged section on the
rear of the crankshaft acts as an oil slinger. While
the crankshaft is out of the engine, handle it care-
fully to prevent damage to the connecting rod
crankpins and the main bearing journals. Refer
to Fig. 85.
E-39. Crankshaft Inspection and Repair
Clean out the drilled oil passages in the crankshaft
journals with a small rifle brush making sure to
get rid of all sludge or gum deposits. Blow out
the passages with compressed air after cleaning.
Clean the crankshaft thoroughly with a suitable
cleaning solvent. Inspect the crankshaft for cracks,
alignment, and condition of the crankpins and the
main bearing journals. Use magnaflux equipment,
if available, to check for cracks or structural flaws.
Cracks, misalignment, and scored or worn journals
and crankpins necessitate crankshaft repair or
replacement.
Check crankshaft counterweights to be sure they
are not loose.
E-40. Checking Crankshaft Alignment
To check alignment, mount the crankshaft in the
cylinder block with the front and rear bearings in
place but with the intermediate bearing removed.
With a dial indicator mounted on the crankcase
and the indicator button resting on the inter-
mediate bearing journal, slowly rotate the crank-
shaft and note the reading on the indicator diaL
Install the intermediate bearing and remove first
the front and then the rear bearings to repeat the
operation with the dial indicator, checking the
front and rear bearing journals. The maximum
allowable run-out is .002" [0,0508 mm.].
l
''t
FIG. 85-CRANKSHAFT AND BEARINGS
1-Bearing Dowel
2-Front Bearing
3-Center Bearing
4-Rear Bearing
.S-Flywheel Bolt
6-Crankshaft
7,-Flywheel Dowel-Bolt
8:_Crankshaft Shim
9-Thrust Washer
10-Woodruff Key No. 9
11-Crankshaft Gear
12-Gear Spacer
13-0il Slinger
E-41. Checking Main Bearing Journals
An ordinary 3
11
[7,62 em.) micrometer may be used.
The standard journal diameter is 2.334C' to
2.3331
11
[5,9286 a 5,9261 em.) for allmain bearings.
Allowable
taper or out-of-round of the journalsis
.001
11
[0,0254 mm.).
E-42. Checking Connecting Rod Crankpins
Check the crankpin diameters with a micrometer
to ensure that they are not out-of-round or tapered
more than .001
11
[0,0254 mm.]The standard crank-
pin diameter is 1.9383
11
to 1.9375
11
[4,9233a 4,9213
em.].
E-43. Deleted.
E-44. Crankshaft Main Bearings
The crankshaft rotates on three main bearings
with a running clearance of .0003" to .0029"
[0,0008
a 0,0103 mm.].
These bearings are positioned and prevented from
rotating in their supports in the· cylinder block by
dowel pins. Dowel pins are used in both the center
and the rear bearing caps. No dowel pins are use<i
in the front bearing cap because the bearing has
a flange. The front main bearing takes the end
thrust of the crankshaft. The main bearings are
of premium type which provides long bearing life.
They are replaceable and when correctly installed,
provide proper clearance without filing, boring,
scraping, or shimming. Crankshaft bearings can
be removed from this engine only with the engine
out of the vehicle. Crankshaft bearings must be
replaced as a complete set of three bearings, each
bearing consisting of two· halves. Main bearings
are available in the standard size and the following
undersizes :
.001" [0,025 mm.] .012
11
[0,304 mm.]
.002
11
[0,050 mm.] .020
11
[0,508 mm.]
.. 010
11
[0,254 mm.] .030
11
[0,762 mm.]
The .001
11
and .002
11
undersize main bearings are
for use with standard size crankshafts having
slightly worn journals. The .010
11
, .020", and .030"
undersize bearings are for use with undersize
crankshafts in those sizes. The .012
11
undersize
bearings are for use with .010
11
undersize' crank-
shafts having slightly worn journals. Bearing sizes
are rubber stamped on the reverse side of each
bearing half.
E-45. Crankshaft Main Bearing Inspection
The crankshaft journals must be carefully inspected
as detailed previously in Par. E-41. Worn journals
will require undersize bearings. Scored, flaked, or
worn bearings must be replaced. Measure the main
bearing bores in the cylinder block using a telescope
gauge and micrometer. Measure the bores at right
angles to the split lfne and at 45° to the split line.
The bores should not be over .001
11
[0,0254 mm.]
out-of-round or .001" in taper from end to end.
Also, the bores should not be more then .001
11
O¥ersize, considering the average diameter of the
bore.
E-46. Fitting Crankshaft Main Bearings
Using Plastigage
After wiping and carefully inspecting the bearing
bore, install the proper bearing. See that the oil
hole in the bearing upper. half registers properly
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