Hummer H2. Manual — part 1795

Fig. 366: Engine Block Rear Oil Gallery Plug
Courtesy of GENERAL MOTORS CORP.

8. Remove the engine block rear oil gallery plug.

9. Inspect the O-ring seal of the rear oil gallery plug.

If the O-ring seal is not cut or damaged, the plug and O-ring seal may be used during assembly.

Fig. 367: Engine Block Front Oil Gallery Plug
Courtesy of GENERAL MOTORS CORP.

IMPORTANT:

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Remove the front oil gallery plug only if service is required.

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If the front oil gallery plug is removed, a NEW oil gallery plug must

2004 Hummer H2

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

10. Remove the engine block front oil gallery plug.

ENGINE BLOCK CLEANING AND INSPECTION

Tools Required

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J 8087 Cylinder Bore Gauge. See Special Tools and Equipment .

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J 42385-100 Thread Repair Kit. See Special Tools and Equipment .

1. Clean the following areas:

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The engine block in the solvent, to remove all sludge, dirt, or debris

Refer to Cleanliness and Care .

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Dry the block with compressed air.

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The gasket surfaces

Refer to Replacing Engine Gaskets .

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The coolant passages

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The oil galleries

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The main bearing caps

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The engine block cylinder head bolt holes for threadlocking material

Thread repair driver tool J 42385-107 may be used to clean the threads of old threadlocking
material.

2. Inspect the following areas:

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The cylinder walls for excessive scratches, gouging, or ring ridge

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The cylinder bores for excessive ring ridge at the top of the cylinder

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The coolant jacket for cracks

be installed.

NOTE:

Do not use a caustic solution to clean the aluminum engine block.

IMPORTANT: When cleaning the engine block in a thermal type oven, do not

exceed 450°F (232°C).

CAUTION: Refer to Safety Glasses Caution in Cautions and Notices.

2004 Hummer H2

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

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The valve lifter bores for excessive scoring or wear

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The crankshaft bearing webs for cracks

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The gasket sealing surfaces for excessive scratches or gouging

Refer to Replacing Engine Gaskets .

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The oil galleries for restrictions

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All threaded bolt holes for damage

3. Measure the following areas:

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The cylinder bores for taper

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The cylinder bores for excessive ring ridge at the top of the cylinder

Measuring the Cylinder for Taper, Out-of-Round, and Oversize

2004 Hummer H2

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

Fig. 368: Measuring J 8087 Dimension
Courtesy of GENERAL MOTORS CORP.

1. Adjust the micrometer to a dimension slightly smaller than the bore size.

Adjust the micrometer to 101.62 mm (4.0 in) for 6.0 liter engines.

Fig. 369: Determining Cylinder Bore Out-Of-Round Using J 8087

2004 Hummer H2

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