Engine Assembly; Measuring Main Bearing Journal Diameter With A Micrometer - Jeep 1987 Wrangler Workshop Manual

JR1
2.5L 1-4 ENGINE OVERHAUL
ENGINE ASSEMBLY
CAUTION: Never use a pair of inserts that differ
more than one bearing size a s a pair. For e x a m -
ple, do not use a standard size upper insert and
a 0.002 inch undersize lower insert.
If the clearance exceeds specification using a
pair of 0.002 inch undersize bearing inserts,
measure the crankshaft journal diameter with a
micrometer (refer to Measuring Main Bearing
Journal Diameter with a Micrometer). If the jour-
nal diameter is correct, the crankshaft bore in
the cylinder block may be misaligned, which re-
quires cylinder block replacement or machining
to true bore. If diameter for journals 1 through 5
is less than 2.4981 inches replace crankshaft or
grind down to accept appropriate under size
bearing inserts.
Measuring Main Bearing Journal Diameter with
a Micrometer (Crankshaft Removed)
Clean the main bearing journal of oil.
Determine the maximum diameter of journal
with a micrometer. Measure at two locations
9 0 ° apart at each end of the journal.
Refer to Specification for maximum allowable
taper and out of round. Compare measured di-
ameter with the journal diameter specification
listed in the Main Bearing Fitting Chart and s e -
lect inserts required to obtain the specified
bearing-to-journal clearance.
Once the proper clearances have been ob-
tained remove the crankshaft and proceed to
crankshaft installation.
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