Crankshaft; Main Bearings - GMC 1976 ZEO 6083 Maintenance Manual

across the machined surface of the rear of the block
and measure from the straight edge to the lip of the
plug . Dimension should be .250" maximum to . 160"
minimum .
REMOVAL
CRANKSHAFT
1 . With engine on stand and oil pan, oil pump
and front cover removed, rotate crankshaft to the
position where the connecting rod nuts are most ac
cessible . Figure 67 shows No . 3 and No . 4 rods in the
fully extended position .
2. Remove main bearing caps .
3 . Remove connecting rod caps and install thread
protectors .
4. Note position of keyway in crankshaft so it can
be installed in the same position .
5 . Lift crankshaft out of block . Rods will pivot to
the center of the engine when the crankshaft is
removed.
Do not allow pistons to move in their bore during
or after crankshaft removal.
Figure 67-Crankshaft Removal
INSTALLATION
ENGINE
6A- 5 9
1 . Install sufficient oil pan bolts in pan rails to
align rods with rubber bands as shown in Figure 67 .
Align rods so that the inner thread protectors of
adjacent rods overlap approximately one inch as
shown . Alignment can be adjusted by increasing ten
sion on rubber bands with additional turns around
the pan bolts or thread protectors .
2. Position upper half of main bearings in block
and lubricate with engine oil.
3 . Install a new rear main bearing seal .
4. After oil passages in crankshaft have been
checked for being open and shaft is clean, place shaft
in block. Lubricate thrust flanges of the center bear
ing with 1050169 Lubricant or equivalent . Install
caps with lower half of bearing lubricated with en-
gine oil. Lubricate cap bolts with No . 1050125 or
equivalent, and install, but do not tighten .
5. With a block of wood (figure 68) bump shaft
in each direction to align thrust flanges of center
main bearing.
NOTE:
After bumping shaft in each direction,
wedge the shaft to the front and hold it while
torquing No . 3 cap bolts.
Figure 68-Aligning Center Main Bearing Flanges