Hummer H2. Manual — part 1827

Fig. 482: Inspecting For Excessive Valve Stem To Guide Clearance
Courtesy of GENERAL MOTORS CORP.

2. A valve stem (1) and guide (2) with excessive clearance must be replaced or the components replaced.

Refer to Engine Mechanical Specifications .

2004 Hummer H2

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

Fig. 483: Inspecting Valves For Damage
Courtesy of GENERAL MOTORS CORP.

3. Inspect the valve stems for excessive scoring, wear, or warpage.

z

A valve stem that has excessive scoring (3 or 4) or wear (4 or 6) must be replaced.

z

A valve guide that is worn and has excessive stem-to-guide clearance should be reamed and valves
with oversize stems installed.

4. Measure the valve stem diameter. A valve stem with a diameter less than 7.95 mm (0.313 in) must be

replaced.

2004 Hummer H2

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

If the valve stem diameter is within specifications, and the stem-to-guide clearance is excessive, the valve
guide must be reamed oversize and a valve with oversize stem installed.

Fig. 484: Reaming Valve Guide Using J 37378-1
Courtesy of GENERAL MOTORS CORP.

5. Ream the valve guide using the J 37378-1 . See Special Tools and Equipment .

6. Clean the guide bore of all metal shavings and debris.

2004 Hummer H2

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

Fig. 485: Valve & Cylinder Head
Courtesy of GENERAL MOTORS CORP.

7. Install the valve (227-228), with oversize stem, into the cylinder head (218).

8. Inspect the valve for the proper fit.

2004 Hummer H2

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