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