Hummer H2. Manual — part 1809

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Scoring to the full-floating design piston pin bore (3) or piston pin

Fig. 417: Upper & Lower Compression Rings & Marks
Courtesy of GENERAL MOTORS CORP.

6. Identify the NEW upper and lower compression rings. The upper compression ring can be identified by a

paint mark (3) located 180 degrees from the end gap. The lower compression ring can be identified by a
paint mark (3) located 90 degrees from the end gap. Both rings should be installed with the orientation
marks (1, 2) facing the top of the piston.

2004 Hummer H2

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

Fig. 418: Measuring Piston Ring-To-Piston Ring Groove Side Clearance
Courtesy of GENERAL MOTORS CORP.

7. Insert the edge of the piston ring into the piston ring groove.

Roll the piston ring completely around the piston. If binding is caused by distorted ring groove, MINOR
imperfections may be removed with a fine file. If binding is caused by a distorted piston ring, replace the
rings as required.

2004 Hummer H2

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

Fig. 419: Measuring Piston Ring Side Clearance With Feeler Gauge
Courtesy of GENERAL MOTORS CORP.

8. Measure the piston ring side clearance with a feeler gauge. If side clearance is not within specifications,

try another piston ring. If the proper ring-to-groove clearance cannot be obtained, replace the first design
press-fit piston, pin, and connecting rod assembly. Refer to Engine Mechanical Specifications .

2004 Hummer H2

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

Fig. 420: Measuring Piston Pin Diameter
Courtesy of GENERAL MOTORS CORP.

9. To determine piston pin-to-bore clearance, use a micrometer and measure the piston pin outside diameter

(OD).

2004 Hummer H2

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