Hummer H2. Manual — part 1796

Courtesy of GENERAL MOTORS CORP.

2. Insert the bore gauge into the micrometer and zero the bore gauge dial.

3. Use the J 8087 or equivalent and measure the cylinder bore for taper, out-of-round, and oversize. See

Special Tools and Equipment .

Slide the bore gauge up and down throughout the length of the cylinder bore. Check the bore both parallel
and perpendicular to the centerline of the crankshaft at the top, center, and bottom of the bore.

A 6.0L cylinder bore that measures 101.618-101.636 mm (4.0007-4.0014 in) may be honed and serviced
with a standard size piston.

A cylinder bore that exceeds the maximum diameter must be serviced with an oversized piston.

CYLINDER BORING AND HONING

Boring Procedure

1. Measure all pistons with a micrometer to determine the cylinder bore diameter.

2. Before you use any type of boring bar, use a fine file and clean the top of the cylinder block removing any

dirt or burrs. If you do not check the cylinder block, the boring bar may be improperly positioned, tilted,
and the cylinder bore could be bored at an incorrect angle.

3. Carefully follow the instructions furnished by the manufacturer regarding use of the equipment.

4. When you bore the cylinders, make sure all the crankshaft bearing caps are in place. Tighten the

crankshaft bearing caps to the proper torque in order to avoid distortion of the cylinder bores during final
assembly.

5. When you take the final cut with a boring bar, leave 0.03 mm (0.001 in) on the cylinder bore diameter for

the finish honing and fit of the piston.

Honing Procedure

IMPORTANT: A 0.5 mm (0.02 in) oversize service piston and a piston ring set are

available for the 6.0 liter engine.

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 370: Cylinder Bore Cross Hatch Pattern
Courtesy of GENERAL MOTORS CORP.

1. When honing the cylinders, follow the manufacturer's recommendations for equipment use, cleaning, and

lubrication. Use only clean, sharp stones of the proper grade for the amount of material you remove. Dull,
dirty stones cut unevenly and generate excessive heat. Do not hone to final clearance with a coarse or
medium-grade stone. Leave sufficient metal so that all stone marks may be removed with fine-grade
stones. Perform final honing with a fine-grade stone, honing the cylinder to the proper clearance.

2. During the honing operation, thoroughly clean the cylinder bore. Repeatedly check the cylinder bore for

fit with the selected piston.

All measurements of the piston or the cylinder bore should be made with the components at normal room
temperature.

3. When honing a cylinder for fit to an oversize piston, first perform the preliminary honing with a 100 grit

stone.

4. Perform final cylinder honing with a 240 grit stone and obtain a 45 degree cross hatch pattern.

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

A 240 grit stone is preferred for final honing. If a 240 grit stone is not available, a 220 grit stone may be
used as a substitute.

5. When honing to eliminate taper in the cylinder, make full strokes the complete length of the bore.

Repeatedly check the measurement at the top, the middle, and the bottom of the bore.

6. The finish marks should be clean but not sharp. The finish marks should also be free from imbedded

particles and torn or folded metal.

7. By measuring the selected piston at the sizing point and by adding the average of the clearance

specification, you can determine the final cylinder honing dimension required.

8. When finished, the reconditioned cylinder bores should have less than or meet the specified out-of-round

and taper requirements.

9. After final honing and before the piston is checked for fit, clean the cylinder bores with hot water and

detergent. Scrub the bores with a stiff bristle brush and rinse the bores thoroughly with hot water. Do not
allow any abrasive material to remain in the cylinder bores. This abrasive material may cause premature
wear of the new piston rings and the cylinder bores. Abrasive material will also contaminate the engine
oil and may cause premature wear of the bearings. After washing the cylinder bore, dry the bore with a
clean rag.

10. Perform final measurements of the piston and the cylinder bore.

11. Permanently mark the top of the piston for the specific cylinder to which it has been fitted.

12. Apply clean engine oil to each cylinder bore in order to prevent rusting.

Deglazing Procedure

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 371: Deglazing Cylinder Bore
Courtesy of GENERAL MOTORS CORP.

Using a ball type or self centering honing tool, deglaze the cylinder bore lightly. Deglazing should be done only
to remove any deposits that may have formed. Use a 240 grit stone of silicone carbide or equivalent material
when preforming the deglazing procedure.

A 240 grit stone is preferred for final honing. If a 240 grit stone is not available, a 220 grit stone may be used as
a substitute.

CRANKSHAFT AND BEARINGS CLEANING AND INSPECTION

Tools Required

z

J 6125-1B Slide Hammer. See Special Tools and Equipment .

z

J 7872 Magnetic Base Dial Indicator Set

z

J 41818 Crankshaft Bearing Cap Remover

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2