Hummer H2. Manual - part 1873

1. Clean the engine block cylinder head bolt holes, if required. 

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

2. Spray cleaner GM P/N 12346139, GM P/N 12377981 (Canadian P/N 10953463) or equivalent into the 

hole.  

3. Clean the cylinder head bolt holes with compressed air. 

NOTE:

Clean all dirt, debris, and coolant from the engine block cylinder head bolt 
holes. Failure to remove all foreign material may result in damaged 
threads, improperly tightened fasteners or damage to components.

IMPORTANT:

z

Do not use the cylinder head bolts again. Install NEW cylinder head 
bolts during assembly.  

z

Do not use any type sealant on the cylinder head gasket, unless 
specified.  

z

The cylinder head gaskets must be installed in the proper direction 
and position.  

 

2004 Hummer H2 

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

  

Fig. 647: 100 mm & 155 mm Bolts 
Courtesy of GENERAL MOTORS CORP. 

4. Measure the depth of the cylinder head bolt holes (1-10) and select the correct length bolts as required.  

5. Check the cylinder head locating pins for proper installation. 

IMPORTANT: First design engine blocks have different drill and tap depths using both 

medium length 100 mm (3.94 in) and long 155 mm (6.1 in) M11 cylinder 
head bolts. Second design engine blocks use only the medium length 100 
mm (3.94 in) bolt with a common drill and tap depth.

 

2004 Hummer H2 

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

  

Fig. 648: Cylinder Head Gasket Displacement Markings 
Courtesy of GENERAL MOTORS CORP. 

6. Inspect the displacement markings (1) on the gasket, for proper usage. 

 

2004 Hummer H2 

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

  

Fig. 649: Cylinder Head Gasket (Right) 
Courtesy of GENERAL MOTORS CORP. 

7. Install the NEW right cylinder head gasket onto the locating pins. 

IMPORTANT: When properly installed, the tab on the right cylinder head gasket will be 

located right of center or closer to the front of the engine.

 

2004 Hummer H2 

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