Engine Assembly And Adjustment; Crankshaft Main Bearing Selection; Crankshaft And Main Bearing Installation - Hummer H1 Service Manual

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2-80 Engine

ENGINE ASSEMBLY AND ADJUSTMENT

Crankshaft Main Bearing Selection

Main bearings are available in standard and two undersizes for
select fit purposes. Required bearing clearances are:
• 0.0017-0.003 in. (0.045-0.083 mm) at bearings 1
through 4
• 0.002-0.0036 in. (0.055-0.093 mm) at number 5 rear
main
There are three main journal diameter ranges. The ranges are
identified by a color code paint mark near one of the journals.
The size range color codes are blue, orange/red, and white.
Rod bearing journals are marked yellow or green. The color
codes indicate journal diameter and correspond to the Main
Bearing Selection Chart at the end of this section.
The main bearing bores in the block are also coded for size.
There are three ranges identified by the numbers 1, 2, or 3.
These numbers are stamped in the cylinder block pan rail. Re-
fer to the Main Bearing Selection chart at the end of this sec-
tion.
NOTE: Different bearings are used in turbo and NA diesel en-
gines. Do not interchange the main or rod bearings.

Crankshaft and Main Bearing Installation

1. Measure main journal diameters, note color code on
crankshaft, and size letter on engine pan rail. Select bear-
ings as needed. 0.0005 in. (0.013 mm) bearings are stan-
dard while 0.001 in. (0.026 mm) bearings are undersize.
2. Identify and separate bearing halves before proceeding.
Bearing upper halves have oil grooves while lower halves
do not. Upper halves go in block while lower halves go in
bearing cap. Extra wide bearing is thrust bearing and is
installed in number 3 position.
3. Install main bearing upper halves in block (Figure 2-153).
Install bearing halves dry. Do not lubricate bearing saddle
in block or back of bearing. Be sure each bearing locating
tab is properly seated in notch machined in block. Also be
sure oil holes in bearing and block are aligned. Thrust
bearing half goes in #3 main bearing saddle.
4. Install main bearing lower halves in bearing caps
(Figure 2-154). Install bearings dry and be sure each
bearing locating tang is seated in bearing cap notch. Thrust
bearing half goes in #3 main cap.
5. Position crankshaft in block. Do not turn the shaft. Just
carefully seat it in bearing upper halves.
6. Position length of plastigauge on each main bearing
journal (Figure 2-155). Cut plastigauge so it extends
across three quarters of journal. Position plastigauge so it
is parallel to crankshaft center line as shown.
TANG
BEARING
SADDLES
Figure 2-153: Installing Crankshaft and Main
Bearing Upper Halves
MAIN BEARING
LOWER HALVES
(PLAIN)
Figure 2-154: Assembling Main Caps and Bearing
Lower Halves
CRANKSHAFT
MAIN
BEARING
UPPER
HALVES
(GROOVED)
MAIN CAPS
TANG
®