Crankshaft Replacement - GMC G Service Manual

6A5-20 7.4 LITER V8
3. Oil pump, as outlined previously.
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. Rear crankshaft oil seal, if necessary, as outlined
previously.
7. 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.
• Main bearing cap replacement (shimming
procedure).
Figure 33 — Removing the Main Bearing
H Install or Connect (Figures 22, 33, and 34)
Tool Required:
J 8080 Main Bearing Remover/Installer
1. Upper main bearing inserts.
• Insert tool 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 the tool.
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.
l^§l Measure
• Main bearing clearance. Refer to the proper unit
repair manual. If the engine is in the vehicle, the
crankshaft must be supported upward to
remove any clearance from the upper bearing.
The total clearance can then be measured
between the lower bearing and journal.
3. Main bearing caps (except rear cap) and bolts to the
block.
Tighten
• Main bearing cap bolts to 150 N*m (110 ft. lbs.).
4. Rear crankshaft oil seal to the block and main bearing
cap, as outlined previously.
5. Rear main bearing cap.
• Apply a brush-on type oil sealing compound to
the mating surface of the block and cap (figure
22). Do not allow any sealant on either crank­
shaft or rear oil seal.
• Apply engine oil to the bearing insert.
• Install the rear main bearing cap and bolts.
Tighten the bolts temporarily to 14 N«m (10 ft.
lbs.).
I^PlI 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.
• Tighten the rear main bearing cap bolts to
150 N«m (110 ft. lbs.).
• With the crankshaft forced fonward, mea­
sure at the front end of the rear main bear­
ing with a feeler gage (figure 34). The
proper clearance is 0.006-0.010-inch
(0.152-0.254 mm).
6. Oil pump, as outlined previously.
7. Oil pan, as outlined previously.
8. Spark plugs.

CRANKSHAFT REPLACEMENT

1. Remove the engine, as outlined later.
2. Refer to the proper unit repair manual for crankshaft
replacement procedures.