Crankshaft Removal; Crankshaft Rear Oil Seal Removal (Without Removing Crankshaft); Main Bearing Removal (Without Removing Crankshaft) - GMC 1989 Light Duty Truck Repair Manual

6A4-12 4.8 LITER L6
Figure 18— Flywheel Installed
4. Bolts (122).
5. Flywheel (118).

CRANKSHAFT REMOVAL

The main bearings and rear oil seal can be replaced
without removing the crankshaft, as outlined later in this
section.
*-► R em ove or D isconnect (Figures 5 and 19)
• Check the main bearing caps (152) for location
markings. Mark the caps if necessary. The caps
must be returned to their original locations during
the engine assembly.
1. Bolts (138) and stud (139).
2. Main bearing caps (137 and 152).
3. Crankshaft (154). Lift the crankshaft straight up,
taking care to avoid dam age to the crankshaft
journals and thrust flange surfaces.
4. Upper and lower seal halves (132 and 135). Pry the
seal halves out with a screwdriver (figure 19).
5. Main bearing inserts (130, 133, 136, and 153). If the
main bearing inserts are to be reused, mark them to
insure they are instralled in their original positions
before removal.
Figure 19— Removing the Lower Seal Half
CRANKSHAFT REAR OIL
SEAL REMOVAL (WITHOUT
REMOVING CRANKSHAFT)
4 -+
Rem ove or D isconnect (Figures 5, 19, and 20)
1. Rear main bearing cap (137).
2. Lower seal half (135) (figure 19).
3. Upper seal half (132).
• Tap on the upper seal half, using a small drift
and hammer (figure
• Remove the upper seal half, using pliers
20
(figure ).
MAIN BEARING REMOVAL
(WITHOUT REMOVING
CRANKSHAFT)
R em ove or D isconnect (Figures 5, 21, and 22)
□
Tool Required:
J-8080 Main Bearing Remover/Installer
• Check the main bearing caps (152) for location
markings. Mark the caps if necessary. The caps
must be returned to their original locations during
assembly.
1. Main bearing caps (137 and 152).
2. Upper and lower seal halves (132 and 135), as
previously described.
3. Upper rear main bearing insert (133).
20
).