Isuzu NHR 4J Series, Workshop Manual

Page: 100 / 406

GENERAL ENGINE MECHANICAL 6A – 33
2. Main bearing clearance
1) Remove the main bearing caps in the sequence
shown in the illustration.
Arrange the removed main bearing caps in the cylinder
number order.
2) Remove the crankshaft. Remove the main bearings.
3) Clean the upper and lower bearings as well as the
crankshaft main journal.
4) Check the bearings for damage or excessive wear.
The bearings must be replace as a set if damage or
excessive wear is discovered during inspection.
5) Set the upper bearings and the thrust washers to their
original positions. Carefully install the crankshaft.
6) Set the lower bearings to the bearing cap original
position.
7) Apply plastigage to the crankshaft journal unit as
shown in the illustration.
8) Install the main bearing caps. Apply engine oil to the
bolt threads and the seats. Tighten the bolts to the
specified torque.
N ∙ m (kg ∙ m/lb ∙ ft)
167 (17/123)
NOTE:
Do not allow the crankshaft to rotate.
9) Remove the main bearing caps.
10) Measure the plastigage width and determine the oil
clearance. If the oil clearance exceeds the specified
limit, replace the main bearings as a set and/or
replace the crankshaft.
11) Clean the plastigage from the bearings and the
crankshaft.
12) Remove the crankshaft and the bearings.
Oil Clearance
mm (in)
Standard Limit
4JB1
/4JB1T
4JB1TC
0.035 - 0.080
(0.0014 - 0.0036)
4JG2
0.031 - 0.063
(0.0012 - 0.0025)
0.11 (0.0043)
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