Crankshaft And Main Bearing Installation - GMC 1989 Light Duty Truck Repair Manual

Unit repair manual
Table of Contents

Advertisement

MAIN BEARING
INSTALLATION (WITH
CRANKSHAFT INSTALLED)
Refer to " Crankshaft and Main Bearing Installation,"
later in th is section for m ain bearing inse rt sizing
information.
- ► +
Install or C onnect (Figures 5 and 21)
Tool Required:
J-8080 Main Bearing Remover/Installer
1. Upper rear main bearing insert (133).
• Apply engine oil to an insert of the proper size.
• Insert the plain end (without the bearing tang)
of the insert between the crankshaft journal
and the notched side of the block (115).
• Use plie rs w ith taped jaw s to clam p the
bearing to the crankshaft (154) as shown in
figure 21. Rotate the crankshaft to " roll" the
insert into the block. Then seat the insert
using a small drift and hammer.
2. Lower rear main bearing insert (136).
• Apply engine oil to an insert of the proper size.
• Press the insert into the rear main bearing cap
(137).
3. Upper main bearing inserts (130).
• Insert J-8080 into a crankshaft main bearing
oil hole.
• Apply engine oil to inserts of the proper size.
• Insert the plain end (without the bearing tang)
of the insert between the crankshaft (154) and
the notched side of the block (115).
• Rotate the crankshaft (154) to " roll" the insert
into the block.
• Remove J-8080.
4. Lower main bearing inserts (153) to the main
bearing caps (152).
• Make sure the inserts are of the proper size.
• Apply engine oil to the inserts.
5. M ain b e a rin g c a p s (137 and 152). R e fe r to
" Crankshaft and Main Bearing Installation" later in
this section.
M easure
m
Main bearing clearance and crankshaft end
p la y.
R e fe r
MECHANICAL (SEC. 6A).
CRANKSHAFT AND MAIN
BEARING INSTALLATION
Main bearings are of the precision insert type and do
not use shims for adjustment. If clearances are found to
be excessive, a new bearing, plus both upper and lower
inserts will be required. Service main bearings are
available in standard size and 0.001-inch, 0.002-inch,
0.010-inch, 0.020-inch and 0.030-inch undersize.
Selective fitting of the main bearing inserts is necessary
in production in order to obtain close tolerances. For this
reason you may use one standard insert with one
0.001-inch undersize insert w hich will decrease the
clearance 0.0005-inch from using two standard inserts.
to
G E N E R A L
E N G IN E
4.8 LITER L6 6A4-25
Apply Sealant to Shaded Areas Only
Figure 49—Applying Sealant to the Block
MAIN BEARING SELECTION
The simplest, most accurate way to measure main
bearing clearance is with the use of gaging plastic. This
wax-like material compresses evenly between the bearing
and journal surfaces without damaging them. Proceed as
follows:
0
Install or C onnect (Figure 5)
1. Upper main bearing inserts (130 and 133) to the
block (115).
• If any undersized bearings are used, make
absolutely certain they are fitted to the proper
journal.
2. Crankshaft (154). Take care not to damage the thrust
areas.
3.
Lower bearing inserts (136 and 153) to the bearing
caps (137 and 153).
M easure
• Main bearing clearance. Refer to GENERAL
ENGINE MECHANICAL (SEC. 6A).
• Apply oil to the main bearing inserts.
4. Rear main bearing cap (137).
• Apply a brush-on type oil sealing compound to
the mating surface of the block and cap (figure
49). Do not allow any s e a la n t on e ith e r
crankshaft or rear oil seal.
• Install the rear main bearing cap.
5. Bolts (138).
Tighten
• Bolts (138) to 14 N m (10 ft. lbs.).
6
Main bearing caps (152) with the selected lower
.
main bearing inserts (153). Be sure to put the main
bearing caps in their original locations, with the
arrows facing the front of the engine.
Bolts (138 and 139). Make sure the special bolt
(139), which retains the oil pump screen bracket, is
installed in the proper position. (#5 main bearing
cap, camshaft side hole.)
B-03498

Hide quick links:

Advertisement

Table of Contents
loading

Table of Contents