GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Engine 🢒 Engine Mechanical - 6.6L (LLY) 🢒 Upper Oil Pan Replacement

Removal Procedure
  1. Remove the oil level indicator.
  2. Remove the transmission. Refer to Transmission Replacement in Automatic Transmission - Allison or Transmission Replacement in Manual Transmission - ZF S6-650.
  3. Remove the lower oil pan. Refer to Lower Oil Pan Replacement .
  4. Remove the engine flywheel. Refer to Engine Flywheel Replacement - Automatic Transmission or Engine Flywheel Replacement - Manual Transmission .

    5. Object Number: 673564 Size: SH
  5. Remove the bolts and the battery positive and negative cable bracket from the front of the upper oil pan.

    6. Object Number: 673568 Size: SH
  6. Remove the nut and the battery positive and negative cable bracket from the right side of the upper oil pan.

    7. Object Number: 660335 Size: SH
  7. Remove the engine flywheel housing to upper oil pan bolts denoted by the black triangles.

    8. Object Number: 739051 Size: SH
  8. Remove the upper oil pan bolts and any brackets. Mark the bolt location of the bracket.
  9. Separate the upper oil pan from the engine block.
  10. Remove the upper oil pan. The oil level indicator tube needs to be removed while lowering the upper oil pan.

    11. Object Number: 663126 Size: SH
  11. Clean the upper oil pan.
  12. Clean the sealing surface on the engine block.
  13. Inspect the upper oil pan for cracks.
  14. Inspect the upper oil pan sealing surfaces and the engine block for damage.

Installation Procedure

    Object Number: 663817 Size: SH
  1. Apply a 2 mm (1/8 in) wide bead of sealant GM P/N 12378521 or equivalent to the upper oil pan mating surfaces.
  2. Apply a 2 mm (1/8 in) wide bead of sealant GM P/N 12378521 or equivalent to engine flywheel housing sealing surface.

    3. Object Number: 739051 Size: SH
  3. Install the upper oil pan to the engine block. Ensure the oil level indicator tube is installed into the upper oil pan.

    4. Object Number: 663823 Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  4. Install the upper oil pan bolts and any brackets.

    5. Tighten
    Tighten the upper oil pan bolts in the proper sequence to 21 N·m (15 lb ft).


    Object Number: 660335 Size: SH
  5. Install the engine flywheel housing to upper oil pan bolts denoted by the black triangles.

    6. Tighten
    Tighten the engine flywheel housing to upper oil pan bolts to 50 N·m (37 lb ft).


    Object Number: 673564 Size: SH
  6. Install the bolts and the battery positive and negative cable bracket to the front of the upper oil pan.

    7. Tighten
    Tighten the cable bracket bolts to 12 N·m (106 lb in).


    Object Number: 673568 Size: SH
  7. Install the nut and the battery positive and negative cable bracket from the right side of the upper oil pan.

    8. Tighten
    Tighten the cable bracket nut to 8 N·m (71 lb in).

  8. Install the engine flywheel. Refer to Engine Flywheel Replacement - Automatic Transmission or Engine Flywheel Replacement - Manual Transmission .
  9. Install the lower oil pan. Refer to Lower Oil Pan Replacement .
  10. Install the transmission. Refer to Transmission Replacement in Automatic Transmission - Allison or Transmission Replacement in Manual Transmission - ZF S6-650.
  11. Lower the vehicle.
  12. Install the oil level indicator.
  13. Fill the engine with oil. Refer to Engine Oil and Oil Filter Replacement .