Hummer H3. Manual — part 392

1. When honing the cylinder bores, 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 to be
removed.

Dull, dirty stones cut unevenly and generate excessive heat.

DO NOT hone to a final grade with a coarse or medium-grade stone.

Leave sufficient metal so that all the stone marks will be removed with the fine grade
stones.

Perform the final honing with a fine-grade stone and hone the cylinder bore in a cross
hatch pattern at 45-65 degrees to obtain the proper clearance.

2. During the honing operation, thoroughly check the cylinder bore.

Repeatedly check the cylinder bore fit with the selected piston.

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

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

the cylinder bore.

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

The finish marks should be clean but not sharp.

The finish marks should be free from imbedded particles or torn or folded metal.

4. When finished, the reconditioned cylinder bores should have less than or meet the specified

out-of-round and taper requirements.

5. After the final honing and before the piston is checked for fit, clean the cylinder bore with

hot water and detergent.

1. Scrub the cylinder bores with a stiff bristle brush.

2. Rinse the cylinder bores thoroughly with clean hot water.

3. Dry the cylinder bores with a clean rag.

4. Do not allow any abrasive material to remain in the cylinder bores.

Abrasive material may cause premature wear of the new piston rings and the
cylinder bores.

Abrasive material will contaminate the engine oil and may cause premature wear

CAUTION: Refer to SAFETY GLASSES CAUTION .

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

of the bearings.

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

7. Permanently mark the top of the piston for the specified cylinder to which it has been fitted.

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

CRANKSHAFT AND BEARING CLEANING AND INSPECTION

Tools Required

J 8087 Cylinder Bore Gauge. See Special Tools.

J 45059 Angle Meter. See Special Tools.

Inspection Procedure

Fig. 412: Inspecting Crankshaft
Courtesy of GENERAL MOTORS CORP.

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

1. Clean the crankshaft of all elements.

2. Inspect the crankshaft oil passages for obstructions.

3. Inspect the crankshaft for the following conditions:

Damaged threads (1)

Damaged mounting faces

Worn crankshaft pin (2)

Wear without any grooves or scratches (3)

Grooves or scoring (3)

Scratches (3)

Pitting or embedded bearing material (3)

Overheating - discoloration (3)

Damaged teeth (4)

IMPORTANT: Use care when handling the crankshaft. Avoid damage to the

reluctor wheel and crankshaft bearing surfaces.

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

Fig. 413: View Of Crankshaft Bearing Inserts
Courtesy of GENERAL MOTORS CORP.

4. Inspect the corresponding crankshaft bearing inserts for embedded material and determine

the source of the material.

IMPORTANT: If cracks, severe gouges or burned spots are found, replace

the crankshaft. Remove slight roughness using a fine
polishing cloth soaked in clean engine oil. Remove any burrs
using a fine oil stone.

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3