Section 2 Engine - Hummer H1 Service Manual

Section 2 Engine

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PISTON/CONNECTING ROD OVERHAUL
Remove and discard the old piston rings. Use a remover/in-
staller tool similar to parallel jaw type tool shown
(Figure 2-116). Discard rings after removal.
Use a ring groove tool to remove carbon and oil deposits from
the ring grooves. Using a section from an old piston ring is not
recommended for this purpose.
Disassembly the piston, and rod as follows:
a. Note piston-to-rod position for assembly reference.
b. Remove retaining rings that secure piston pin. Discard
rings; they are not reusable.
c. Push piston pin out of piston and rod.
d. Separate piston, and rod, and pin (Figure 2-117).
Clean the piston, rod, and pin with solvent and carb cleaner if
needed. Do not use a wire brush or any type of abrasive on the
piston.
Inspect piston condition. Replace the piston if cracked, se-
verely scuffed or scored, the ring lands are worn or damaged,
or the skirt is collapsed (Figure 2-118).
Measure pin bore diameter in the piston (Figure 2-119). Then
measure diameter of the piston pin (Figure 2-119). The differ-
ence between pin diameter and bore diameter, should be
0.0004 - 0.0006 in. (0.010-0.0153 mm). This figure represents
the required pin-to-bore clearance. Replace the piston and pin
as a set if clearance is greater than specified.
NOTE: Turbo diesel and NA diesel piston and rod assemblies
are different. Do not interchange them.
PISTON RING
REMOVER/INSTALLER
TOOL
Figure 2-116: Piston Ring Removal/Installation Tool
05745159
TOP COMPRESSION RING
BOTTOM
COMPRESSION
RING
OIL RING
ASSEMBLY
PISTON
PISTON PIN
RETAINING RING
PIN BUSHING
CONNECTING ROD
ROD CAP
Figure 2-117: Connecting Rod and Piston Assembly
CROWN
Figure 2-118: Piston Inspection Points
Engine 2-67
RETAINING RING
ROD
BOLT
GROOVE
LAND
PIN BORE
SKIRT