Main Bearing Replacement - GMC G Service Manual

Figure 32 — Measuring Connecting Rod Side
Clearance

MAIN BEARING REPLACEMENT

R Remove or Disconnect (Figure 33)
Tool Required:
J 8080 Main Bearing Remover/Installer
1. Sparkplugs.
2. Oil pan. Refer to "Oil Pan Replacement" in this
section.
3. Oil pump. Refer to "Oil Pump Replacement" in this
section.
4. Main bearing caps.
• Check the main bearing caps for location mark­
ings. Mark the caps if necessary. The caps
must be returned to their original locations dur­
ing assembly.
5. Lower main bearing inserts from the main bearing
caps.
6. Upper main bearing inserts.
• Insert J 8080 into the crankshaft oil hole (figure
33).
• Rotate the crankshaft to "turn" the bearing insert
out of the block.
Cleaning, Inspection, And Repair
Clean, inspect, and repair or replace the components as
required. Refer to the proper Unit Repair Manual. The Unit
Repair Manual contains information on:
• Crankshaft.
• Main and connecting rod bearings.
M Install or Connect (Figures 33 and 34)
Tool Required:
J 8080 Main Bearing Remover/Installer
4.3 LITER V6 6A3-23
1. Upper main bearing inserts.
• Insert J 8080 into a crankshaft main bearing oil
hole (figure
33).
• Apply engine oil to inserts of the proper size.
• Insert the plain end (without the bearing tang) of
the insert between the crankshaft and the
notched side of the block.
• Rotate the crankshaft to "roll" the insert into the
block.
• Remove J 8080.
2. Lower main bearing inserts to the main bearing caps.
• Make sure the inserts are of the proper size.
• Apply engine oil to the inserts.
|t j|l Measure
• Main bearing clearance. Refer to the proper
Unit Repair Manual. If the engine is in the vehi­
cle, the crankshaft must be supported upward
to remove any clearance from the upper bear­
ing. The total clearance can then be measured
between the lower bearing and journal.
Main bearing caps (except rear cap) and bolts to the
3.
block.
H O Tighten
• Main bearing cap bolts to 110 N»m (80 ft. lbs.).
4. Rear main bearing cap.
• Apply engine oil to the bearing insert.
• Install the main bearing cap and bolts. Tighten
the bolts temporarily to 14 N»m (10 ft. lbs.).
R jfl Measure
• Crankshaft end play, as follows:
• Tap the end of the crankshaft first rear­
ward then forward with a lead hammer.
This will line up the rear main bearing and
crankshaft thrust surfaces.