Main Bearing Removal (W Ithout Removing C Ra N K S H A; Cleaning, Inspection, And Repair - Chevrolet 1988 Light Duty Truck Repair Manual

6A3-10 4.3 LITER V
MAIN BEARING REMOVAL
(WITHOUT REMOVING
CRANKSHAFT)
R em o ve or D isco nn ect
Tool Required:
J 8080, Main Bearing Remover/Installer
1. Main bearing caps.
• Check the main bearing caps for location
markings. Mark the caps if necessary. The
ca ps m ust be re tu rn e d to th e ir o rig in a l
locations during assembly.
2. Lower main bearing inserts from the main bearing
caps.
3. Upper main bearing inserts.
• Insert J 8080 into the cra n ksh a ft oil hole
(figure 13).
• Rotate the crankshaft to turn the bearing insert
out of the block.

CLEANING, INSPECTION, AND REPAIR

A solvent tank, large enough to hold the larger engine
parts, will be needed along with various bristle brushes
and a gasket scraper. A source of compressed air will be
helpful in the cleaning operations.
Precision measuring tools will ' a required for the in­
spection procedure. These include: micrometers, cylinder
bore gage, feeler gages, dial Indicator set, etc. The in­
spection work, performed with the prop ' method and
tools, is most important. The rebuilt eng
pected to perform properly if parts wor , beyond accepta­
ble limits are reused.
BLOCK
I J I Clean
1. Block in solvent.
2. Block gasket surfaces.
3. Cylinder bores.
4. Oil galleries and passages.
5. Scale deposits from the coolant passages.
Inspect
1. All expansion plugs for lack of fit or leakage.
2. Valve lifter bores for deep scratches and varnish
deposits.
3. Block for cracks.
— C ylinder walls.
— C oolant jackets.
— Main bearing webs.
— Engine mount bosses.
4. Main bearing bores and main bearing caps.
— All main bearing bores should be rounded and
uniform in ID at all bearing supports.
— The area w here the main bea rin g inserts
co n ta ct the main bearing bore should be
smooth.
-6
cannot be ex­
— If a main bearing cap is damaged and requires
replacem ent, replace it.
5. H ea d g a s k e t s u rfa c e
straightedge and feeler gage. M inor irregularities
may be carefully machined. If more than 0.25 mm
(0.010-inch) must be removed, replace the block.
6. Oil pan rail and tim ing cover attaching area for
nicks. Minor irreqularities may be cleaned up with a
flat file.
CYLINDER BORE
In sp ect
C ylinder bores for scoring or other damage.
m
M easu re
• C ylin d e r bore ta p e r and out-of-round. Refer to
GENERAL ENGINE MECHANICAL (SEC. 6A).
Cylinder Bore Reconditioning
Refer to GENERAL ENGINE MECHANICAL (SEC. 6A).
PISTON AND CONNECTING
ROD ASSEMBLY
Refer to GENERAL ENGINE MECHANICAL (SEC. 6A)
and perform the following:
❖ D isassem b le
Com ponents as required.
1 3 1
C lean
Com ponents as outlined.
In sp ect
Com ponents as outlined.
fo r fla tn e s s . U se a