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4 DLT ENGINE
C
heck crank case main bearing parent bore
dimensions - Refer Figure 71
S
ince a slight clearance exists between main bearing
cap dowel pins and corresponding dowel holes in crank
case. It is possible that main bearing cap once
removed may be installed off center, by which
dimension of main bearing parent bore will be different
in different direction. If there is a difference noticed in
main bearing parent bore dimension, main bearing cap
can be centralized by lightly tapping it with mallet in
required direction after slightly loosening main bearing
cap mounting bolts.
I
f main bearing parent bore is slightly more than
maximum permissible limits, it is possible to reclaim
crank case Main bearing cap mating surface may be
slightly faced after removing dowels. Parent bore
should then be finished on a suitable line boring
machine or with special reamer after fitting new dowels.
I
nstall new pairs of main bearing shells according to
size of crank shaft main bearing journal diameter,
making sure that securing lugs of bearing shells are
properly seated in grooves of crank case and main
bearing caps.
I
nstall main bearing caps with bearing shells in their
respective position on crank case.
T
ighten main bearing cap mounting bolts to specified
torque - Refer Figure 72.
M
easure main bearing bore - Refer Figure 73.
IF MAIN BEARING PARENT BORE DIMENSION IS
MAINTAINEDWITHIN SPECIFIED LIMITS, PROPER
MAIN BEARING BORE DIMENSION
IS
AUTOMATICALLY ACHIEVED.
H
owever it must be physically measured and
confirmed.
Fig. 71
Fig. 72
Fig. 73