SERVICE MANUAL NUMBER 25
262 CID (4.3L) ENGINES
Main Bearings
IMPORTANT: Before removing main bearing caps or connecting rod caps, mark them
for reassembly in their original locations.
Main bearings are of the precision insert type and do not use shims for adjustment. If
clearances are found to be excessive, a new bearing, both upper and lower halves, will be
required. Service bearings are available in standard size and .001 in., .010 in. and .020 in.
undersize.
Selective fitting of both rod and main bearing inserts is necessary in production in order to
obtain close tolerances. For this reason you may find one half of a standard insert with one
half of a .001 in. undersize insert which will decrease the clearance .0005 in. from using a
full standard bearing.
IMPORTANT: If crankshaft has an undersize journal and a new bearing is required,
journal must be reconditioned to accept a .010 or .020 in. undersize bearing as .009
in. undersize bearings are not available for service.
Inspection
In general, the lower half of the bearing (except No. 1 bearing) shows a greater wear and
the most distress from fatigue. If, upon inspection, the lower half is suitable for use, it can
be assumed that the upper half is also satisfactory. If the lower half shows evidence of wear
or damage, both upper and lower halves should be replaced. Never replace one half without
replacing the other half.
Checking Clearances
To obtain accurate measurements while using Plastigage, or its equivalent, engine must be
out of the boat and upside down so crankshaft will rest on the upper bearings and total clear-
ance can be measured between lower bearing and journal.
To ensure the proper seating of the crankshaft, all bearing cap bolts should be at their
specified torque. In addition, before to checking fit of bearings, the surface of the crankshaft
journal and bearing should be wiped clean of oil.
1.
With the oil pan and oil pump removed, remove bearing cap and wipe oil from journal
and bearing cap to be inspected.
2.
Place a piece of gauging plastic the full width of the bearing (parallel to the crankshaft)
on the journal as shown.
a
b
72357
a - Gauging Plastic
b - Journal
Index
90-861328--1
NOVEMBER 1999
Page 3A-69
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 1262 CID, Mercury MerCruiser 262 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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