Dodge ZB 2005 Service Manual page 727

9 - 66 ENGINE
CRANKSHAFT MAIN
BEARINGS
DESCRIPTION
Fig. 112 Main Bearing Identification
The main bearing caps are not interchangeable
and should be marked at removal to insure correct
assembly. Upper and lower main bearing halves are
NOT interchangeable. Lower main bearing halves of
No. 1, No. 2, No. 4, No. 5 and No. 6 are interchange-
able. Upper main bearing halves of No. 1, No. 2, No.
4, No. 5 and No. 6 are interchangeable.
Upper and lower No. 3 bearing halves are flanged
to carry the crankshaft thrust loads and are NOT
interchangeable with any other bearing halves in the
engine (Fig. 112). All bearing cap bolts removed dur-
ing service procedures are to be cleaned and oiled
before installation. Bearing shells are available in
standard and the following undersizes: 0.025 mm
(0.001 in.), 0.051 mm (0.002 in.), 0.076 mm (0.003
in.), 0.254 mm (0.010 in.), 0.305 mm (0.012 in.) and
0.508 mm (0.020 in.). Never install an undersize
bearing that will reduce clearance below specifica-
tions.
STANDARD PROCEDURE
MEASURING CRANKSHAFT MAIN BEARING
CLEARANCE IN-CAR
PLASTIGAGE METHOD
Engine crankshaft bearing clearances can be deter-
mined by use of Plastigage or equivalent. The follow-
ing is the recommended procedure for the use of
Plastigage:
(1) Remove oil film from surface to be checked.
Plastigage is soluble in oil.
(2) The total clearance of the main bearings can
only be determined by removing the weight of the
Fig. 113 Placement of Plastigage in Bearing Shell
1 - PLASTIGAGE
crankshaft. This can be accomplished by either of two
methods:
PREFERRED METHOD
(1) Shimming the bearings adjacent to the bearing
to be checked in order to remove the clearance
between upper bearing shell and the crankshaft. This
can be accomplished by placing a minimum of 0.254
mm (.010 inch) shim (e. g. cardboard, matchbook
cover, etc.) between the bearing shell and the bearing
cap on the adjacent bearings and tighten bolts to
14-20 N·m (10-15 ft.lb.)
• When checking No. 1 main bearing. Shim No. 2
main bearing.
• When checking No. 2 main bearing. Shim No.1
and No. 3 main bearing.
• When checking No.3 main bearing. Shim No. 2
and No. 4 main bearing.
• When checking No. 4 main bearing. Shim No. 3
and No. 5 main bearing.
• When checking No. 5 main bearing. Shim No. 4
and No. 6 main bearing.
• When checking No. 6 main bearing. Shim No. 5
main bearing.
NOTE: REMOVE ALL SHIMS BEFORE REASSEM-
BLING ENGINE
ALTERNATIVE METHOD
(1) With the weight of the crankshaft being sup-
ported by a jack under the counterweight adjacent to
the bearing being checked.
(2) Place a piece of Plastigage across the entire
width of the bearing shell in the cap approximately
6.35 mm (1/4 inch) off center and away from the oil
holes (Fig. 113). (In addition, suspect areas can be
checked by placing the Plastigage in the suspect
area). Torque the bearing cap bolts of the bearing
being checked to the proper specifications.
ZB