Tools Required

EN-48108  Rear Main Oil Seal Installer

Fig 1: EN-48108 Rear Main Oil Seal Installation Tool
Courtesy of GENERAL MOTORS CORP.
NOTE: Do not remove protective nylon sleeve prior to installation. The rear main oil seal installation tool is designed to install the rear main seal with the protective sleeve in place. Never apply or use any oil, lubricants or sealing compounds on the crankshaft rear main oil seal.
NOTE: Clean the crankshaft sealing surface with a clean, lint free towel. Inspect lead-in edge of crankshaft for burrs/sharp edges that could damage the rear main oil seal. Remove burrs/sharp edges with crocus cloth before proceeding.
1. The EN-48108  tool has a unique design to allow the technician to easily install the rear main seal squarely to the correct depth and direction. Before proceeding with installation, review the above illustration to become familiar with the following components:
   • Mandrel (1)
   • Drive Drum (2)
   • Drive Nut (3)
   • Washer (4)
   • Bearing (5)
Fig 2: Aligning Mandrel Dowel Pin
Courtesy of GENERAL MOTORS CORP.
2. Align the mandrel dowel pin to the dowel pin hole in the crankshaft.
Fig 3: Tightening/Loosening Mandrel Screws
Courtesy of GENERAL MOTORS CORP.
3. Using a large flat blade screwdriver, tighten the two mandrel screws to the crankshaft, ensuring the mandrel is snug to the crankshaft hub.
Fig 4: Attaching Seal To Mandrel
Courtesy of GENERAL MOTORS CORP.
IMPORTANT: The seal will only fit one way onto the mandrel, and if properly installed, will center on a step that protrudes from the center of the mandrel.
4. Install the rear main seal (1), with the protective nylon sleeve attached (2), onto the mandrel.
Fig 5: Installing Outer Drive Drum
Courtesy of GENERAL MOTORS CORP.
5. Install the outer drive drum onto the mandrel.
6. Install the bearing, washer, and the drive nut onto the threaded shaft.
Fig 6: Pressing Seal Into Bore
Courtesy of GENERAL MOTORS CORP.
7. Using a wrench, turn the drive nut on the mandrel, which will push the seal into the engine block bore.
8. Turn the wrench until the drive drum is snug and flush against the engine block.
9. Loosen and remove the drive nut, washer, bearing and drive drum. Discard the nylon plastic seal protector.
10. Verify that the seal has seated properly.
Fig 7: Tightening/Loosening Mandrel Screws
Courtesy of GENERAL MOTORS CORP.
11. Use a flat blade screwdriver to remove the two attachment screws from the mandrel and remove the mandrel from the crankshaft hub.