Crankshaft Replacement; Flywheel Replacement; Engine Mountings - GMC G Service Manual

CRANKSHAFT REPLACEMENT

1. Remove the engine. Refer to "Engine Replacement"
in this section.
2. Refer to the proper Unit Repair Manual for crankshaft
replacement procedure.

FLYWHEEL REPLACEMENT

H Remove or Disconnect (Figure 40)
1. Transmission, clutch housing and clutch. Refer to
TRANSMISSION AND CLUTCH (SEC. 7).
2. Rear main bearing cap. Refer to "Rear Crankshaft Oil
Seal Replacement" in this section.
• Mark the flywheel and crankshaft so the dowel pin
holes can be aligned in their original positions at
assembly (figure 40).
• Loosen the flywheel bolts a few turns.
3. Flywheel dowel pins.
• Turn the crankshaft so that a dowel pin is at the
6 o'clock position.
• Drive the dowel pin out using a hammer and
drift.
• Repeat the preceding steps to drive out the
remaining dowel pins. The crankshaft must be
turned to the six o'clock position each time so
that the pin can be driven out without contacting
the block.
4. Flywheel bolts.
5. Flywheel.
M Clean
• Mating surfaces of crankshaft and flywheel. Remove
any burrs.
lLy l Inspect
• Flywheel for burning, scoring, warping, and wear.
Replace the flywheel if necessary. Do not machine
the flywheel.
• Flywheel ring gear for worn or broken teeth.
Flywheel Ring Gear Replacement
1. Use a torch to heat the gear around the entire circum­
ference, then drive the gear off the flywheel, using
care not to damage the flywheel.
NOTICE: Never heat starter gear to red heat as
this will change metal structure.
2. Uniformly heat the flywheel gear to temperature
which will expand the gear to permit installation. Tem­
perature must not exceed 204 degrees C (400
degrees F).
3. As soon as the gear has been heated, install on the
flywheel.
4.8 LITER L6 6A7-23
Figure 40 — Flywheel Dowel Pin Hole Locations
H Install or Connect (Figure 40)
1. Flywheel to the crankshaft. Align the marks made at
disassembly. Make sure the dowel holes in the crank­
shaft and flywheel are aligned.
2. Flywheel.
E 5 I Tighten
• Bolts to 150 N»m (110 ft. lbs.).
3. Dowel pins.
• The interference fit dowel pins must be replaced
with an oversized dowel pin when installing the
flywheel.
• Ream the dowel pin holes to the proper size
(0.4510-0.4517-inch).
• Tap the dowel pins into place, flush with the
flywheel retaining bolt surface.
4. Rear main bearing cap. Refer to "Rear Crankshaft Oil
Seal Replacement" in this section.
5. Transmission, clutch housing and clutch. Refer to
TRANSMISSION AND CLUTCH (SEC. 7).

ENGINE MOUNTINGS

NOTICE: Broken or deteriorated mountings can
cause misaligned and eventual destruction of
certain drive train components. When a single
mounting breakage occurs, the remaining
mountings are subjected to abnormally high
stresses.
B-04556