Hummer H1 (2002+). Manual — part 27

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Engine 2-69

®

05745159

• If a cylinder bore only requires honing to correct a prob-

lem, use the next grade size piston. Avoid going to the
largest oversize piston unless absolutely necessary.

• Verify that a new piston is properly aligned on the con-

necting rod. The rod ID mark and the relief (combustion
chamber) in the piston crown should be on the same
side.

Piston and Connecting Rod Assembly

1.

Lubricate piston pin, pin bore in piston, and bushing in rod
with engine oil.

2.

Install new bolts in rod and install rod cap.

3.

Start pin and piston bore.

4.

Position piston on rod. Relief in piston crown and rod
bearing tangs/notches must be aligned (Figure 2-122).

5.

Push piston pin through rod to secure it to piston.

6.

Install piston pin retaining rings as follows:

a.

Place piston/rod assembly on clean section of work-
bench.

b.

Install tool J–39507 on one end of piston pin
(Figure 2-123).

c.

Start first retaining ring in piston pin bore
(Figure 2-124). Position open end of ring downward
toward bottom of piston.

d.

Use plastic or tape covered pry tool to work ring into
pin bore.

e.

Insert tool J–39507 into piston pin (Figure 2-122).
Place tool tab on retaining ring. Seat ring by pressing
downward and rotating tool in arc. Tool tab will press
ring into place as it is rotated (Figure 2-125).

f.

Remove pin tools and install opposite retaining ring
as described in steps c through e.

Figure 2-122: Piston and Connecting Rod Alignment

Figure 2-123: Positioning Pin for Installation of First

Retaining Ring

Figure 2-124: Starting Retaining Ring in Piston

Pin Bore

PISTON CROWN

RELIEF

LOCATION OF
ROD BEARING

TANGS/NOTCHES

INSTALLER TOOL

J–39507

PISTON PIN

RETAINING RING

TOOL

J–39507

(ON PIN)

RETAINING RING

(MUST EXTEND

BEYOND NOTCH

AND OPEN

END DOWN)

PISTON PIN BORE

2-70

Engine

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Figure 2-125: Seating Piston Pin Retainer Ring

Piston Ring Installation

1.

Check end gap of all rings. Insert ring in bore and push it
down until its about 1-2 inches (2.5-5 cm) below top edge
of bore. Verify that ring is level, then check end gap with
feeler gauge (Figure 2-126). Correct end gaps are:

• Oil ring is 0.009-0.020 in. (0.25-0.51 mm)

• Bottom compression ring is 0.029-0.039 in. (0.75 -1.00

mm)

• Top compression ring is 0.010-0.020 in. (0.26-0.51 mm)

2.

If ring end gap is correct, proceed to step 3. But if gap is
incorrect proceed as follows:

a.

If gap is only a few thousandths/mm too small, file or
grind one ring end to obtain specified gap.

b.

If gap is almost non-existent, or ring ends overlap,
rings are wrong size.

c.

If end gap is larger than specified by only a few
thousands/mm, this indicates bore is slightly worn.
Rings may be retained.

Figure 2-126: Checking Piston Ring End Gap

3.

Install rings in sequence: oil ring first, bottom
compression ring second, and top compression ring last.
Use ring expander tool J–42525 to install the rings.

4.

Position ring end gaps as shown (Figure 2-127). This
avoids ring gap alignment which will cause loss of
compression, blow by, and oil consumption.

5.

Cover and store the piston and rod assemblies on a
workbench prior to installation.

Figure 2-127: Recommended Positioning of Piston

Ring Gaps

INSTALLER TOOL

J–39507

TOOL TAB

RETAINING

RING

FEELER GAUGE

PISTON RING

A

B

C

D

A - OIL CONTROL RING EXPANDER GAP
B - BOTTOM COMPRESSION RING GAP
C - OIL CONTROL RING GAP
D - TOP COMPRESSION RING GAP

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Engine 2-71

®

05745159

CAMSHAFT, TIMING CHAIN, SPROCKET, AND
DRIVE GEAR SERVICE

Clean the camshaft and geartrain parts in solvent. Wipe the
cam dry with shop towels only. Compressor can be used to dry
the other parts.

Inspect the cam bearing journals for wear, scoring, scuffing, or
discoloration from overheating. Replace camshaft if damaged
or discolored (Figure 2-128).

Inspect oil pump drive gear on camshaft for damage. Replace
camshaft if gear teeth are worn, chipped, or broken.

Measure bearing journal wear. Journals 1, 2, 3, and 4 should be
2.164-2.166 in. (54.975-55.025 mm). Journal 5 should be
2.007-2.009 in. (50.975-51.025 mm).

Mount the camshaft on “V” blocks and measure lift. Lift for
both intake and exhaust valve lobes should be 0.281 ± 0.002 in.
(7.133 ± 0.050 mm). Replace camshaft if any lobe is worn be-
low specified range.

Inspect both sprockets for cracks, or chipped, broken teeth. Re-
place sprockets as a matched set if either one is damaged.

Inspect the timing chain for distortion, stretch, or binding. Re-
place the chain if damaged.

Inspect the fuel injection pump drive and driven gears for
cracks, chipped or broken teeth, and wear. Replace both gears
as a set if either one is damaged.

Inspect the thrust plate and spacer for wear. Replace either part
if damaged or worn.

Figure 2-128: Camshaft and Geartrain

FRONT COVER AND OIL FILLER TUBE

Inspect the cover for cracks, scratches/nicks on the sealing sur-
faces, or damaged threads. Remove minor scratches/nicks with
180 grit emery. Repair thread damage with helicoil inserts. Re-
place part if damaged (Figure 2-129).

Inspect the adapter plate for cracks, scratches on mating and
sealing surfaces, dents, pitting, and corrosion. Repair minor
scratches with 180 grit emery. Replace the plate if cracked or
bent.

Figure 2-129: Front Cover Inspection Points

Inspect the oil filler tube grommet. Replace the grommet if
cracked, brittle, or loose (Figure 2-130).

Inspect the oil filler tube. Replace the tube if cracked or dis-
torted (Figure 2-131).

Inspect the filler cap sealing gasket. Replace the cap if the gas-
ket is missing or damaged. Replace the cap if damaged.

Figure 2-130: Adapter Plate Inspection Points

INJECTION PUMP

DRIVE GEAR

INJECTION PUMP

DRIVEN GEAR

TIMING CHAIN

CAMSHAFT SPROCKET

THRUST PLATE

SPACER

CAMSHAFT

OIL PUMP

JOURNAL

LOBE

CRANKSHAFT

SPROCKET

DRIVE GEAR

REAR

SURFACE

SEALING

SURFACE

SEALING

FRONT

THREADED

HOLES

OIL FILLER

TUBE GROMMET

ADAPTER PLATE

SEALING

SURFACE

FRONT SEALING SURFACE

REAR

2-72

Engine

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Figure 2-131: Oil Filler Tube and Cap

CYLINDER HEAD OVERHAUL

Disassembly

1.

Remove glow plugs and injectors if not previously
removed.

2.

Remove temperature sender from left side head
(Figure 2-132).

Figure 2-132: Temperature Sender Removal/

Installation

3.

Clean valve faces with wire brush and measure amount
valves are recessed in head with dial indicator. Intake
valves should be recessed approximately 0.001 in. (0.034
mm) and exhaust valves approximately 0.002 in. (0.048
mm). Recessing means valve faces are positioned below
cylinder head combustion chamber surface.

• If valves extend or protrude above chamber surface, en-

gine is equipped with wrong valves, or heads have been
mismachined.

• If valves are recessed to at least the stated values, con-

tinue with disassembly.

4.

Remove valve assembly in sequence as follows:

a.

Compress valve spring with compressor tool J–8062
(Figure 2-133).

b.

Remove valve locks (Figure 2-134).

c.

Release and remove compressor tool.

d.

Remove valve retainer, shield and spring.

e.

Remove stem seal from valve and slide valve out of
guide and head.

f.

Remove shim.

g.

On exhaust valve, also remove nylon stem and guide
seal (Figure 2-134).

h.

Remove remaining valve assemblies in same manner.

i.

Keep valve parts together on workbench or use
yardstick with drilled holes to keep valve assemblies
separate.

NOTE:

Do not intermix the valve parts as intake and exhaust

valve are different. In addition, the exhaust valves have two
stem seals and a rotator style spring retainer.

Figure 2-133: Compressing Valve Spring

(to Remove Locks)

5.

Mark position of pre-combustion chambers in each
cylinder head (Figure

2-135). Ideally, chambers (if

reused), should be installed in same location in head.

6.

Remove prechambers from cylinder heads (Figure 2-135).
Use a round pry tool to loosen and start each chamber out
of seat in cylinder head.

7.

Remove cover and gasket from right side head
(Figure 2-136).

OIL FILLER TUBE

CAP

TEMPERATURE SENDER

VALVE

SPRING

COMPRESSOR

TOOL J–8062