Hummer H2. Manual - part 856

Fig. 24: Frettage 
Courtesy of GENERAL MOTORS CORP. 

Corrosion set up by a small relative movement of parts with no lubrication. Replace the bearing. Clean all the 
relative parts. Check the seals. Check for proper fit and lubrication. Replace the shaft if damaged. 

Smears 

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Rear Drive Axle - Hummer H2

  

Fig. 25: Smears 
Courtesy of GENERAL MOTORS CORP. 

Smearing of metal due to slippage. Slippage can be caused by poor fits, lack of lubrication, overheating, 
overloads or handling damage. Replace the bearing. Clean all the related parts. Check for proper fit and 
lubrication. 

REAR AXLE LUBRICANT LEAK DIAGNOSIS 

Rear axle lubricant leaks can occur at the following locations: 

z

Axle tube to differential carrier housing joint  

z

Axle shaft oil seal  

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Rear Drive Axle - Hummer H2

  

z

Axle housing porosity  

z

Differential housing cover gasket  

z

Drain plug  

z

Fill plug  

z

Pinion yoke oil seal  

z

Vent tube  

Determining the Cause 

While most rear axle leaks may be easy to find, determining the cause may not be. A thorough inspection of the 
area around the leak may assist in determining the cause of the leak. 

Oil Seals 

Lubricant leaks from a oil seal may be caused by any of the following: 

z

An improperly installed seal  

z

A distorted seal  

z

A worn seal  

z

A worn shaft  

z

A brittle seal lip  

z

A hardened seal lip  

To determine the actual cause of the leak, clean the area around the leak. Observe the area of the leak and 
determine the if the seal or another component is causing the leak. A worn seal surface will cause a leak at the 
sealing lip while a misaligned seal or a seal installed into a housing with an excessive bore will cause the seal to 
leak at the outside surface of the seal. Hardened or cracked seal lips usually indicate the axle is operating 
beyond the normal temperature limits for the axle. A seal whose sealing surface has been nicked or cut may 
indicate that the shaft has a rough, burred, or gouged surface and will need to be inspected before the seal can 
be replaced. 

Gaskets 

A leak at a gasket is usually caused by a poor fit of the components on each side of the gasket surface. Inspect 
each component for distortion and for nicks or gouges that may prohibit the gasket from sealing properly. 

Rear Axle Housing 

Rear axle housing lubricant leaks usually occur at the following locations: 

z

Drain Plug  

z

Fill Plug  

Drain and fill plug leaks are usually caused by a loose plug. These leaks can by repaired by either tightening the 

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Rear Drive Axle - Hummer H2

  

plug or by using an approved sealer on the threads on the plug.

Other leaks such as axle tube to differential carrier housing or porosity leaks require the replacement of the rear 
axle housing. 

REPAIR INSTRUCTIONS 

LUBRICANT LEVEL INSPECTION - REAR DRIVE AXLE 

1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.  

2. Make sure the vehicle is level.  

3. Inspect the rear axle for leaks. Repair as necessary.  

4. Clean the area around the rear axle fill plug. 

Fig. 26: Rear Drive Axle Fill Plug 
Courtesy of GENERAL MOTORS CORP. 

5. Remove the rear axle fill plug.  

6. Inspect the lubricant level. 

Specification: The lubricant level should be between 0-10 mm (0-0.4 in) below the fill plug opening.

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Rear Drive Axle - Hummer H2