GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Astro - 4WD 🢒 Engine 🢒 Engine Mechanical - 4.3L 🢒 Oil Pan Replacement

Removal Procedure

    Object Number: 188048 Size: SH

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Disconnect the battery negative cable. Refer to Battery Replacement in Engine Electrical.
  2. Remove the oil level indicator.
  3. Raise the vehicle and support it with approved safety stands. Refer to Lifting and Jacking the Vehicle in General Information.
  4. Remove the oil pan drain plug and drain the engine oil into a suitable container.
  5. Remove the oil filter.

    6. Object Number: 48327 Size: SH
  6. Remove the bolt holding the oil cooler pipes bracket to the oil pan.
  7. Remove the oil filter adapter. Refer to Oil Filter Adapter and Bypass Valve Assembly Replacement .

    8. Object Number: 327996 Size: SH
  8. Remove the bolt holding the bracket for the starter wiring harness and the transmission cooler pipes.
  9. Remove the crankcase position (CKP) sensor wiring harness from the retainer.
  10. Remove the starter. Refer to Starter Motor Replacement in Engine Electrical.

    11. Object Number: 334324 Size: SH
  11. Remove the transmission cover.

    12. Object Number: 161379 Size: SH
  12. Remove the inner axle shaft housing support bracket to the frame nuts and the washers (Four Wheel Drive only).

    13. Object Number: 6833 Size: SH
  13. Remove the front differential carrier upper and lower mounting nuts and bolts (Four Wheel Drive only).
  14. Lower the front differential carrier assembly only enough for removal of the oil pan.

    15. Object Number: 331034 Size: SH
  15. Remove the access plugs for the oil pan rear nuts.

    16. Object Number: 31739 Size: SH
  16. Remove the following oil pan fasteners:
    17. • Remove the oil pan bolts.
    • Remove the two nuts at the crankshaft rear oil seal housing.
    • Remove the transmission to oil pan bolts and nuts.
  17. Remove the oil pan from the engine. Refer to Oil Pan Removal .
  18. Clean all sealing surfaces on the engine and the oil pan. Refer to Oil Pump Clean and Inspect .

Installation Procedure

    Object Number: 31739 Size: SH
  1. Install the oil pan to the engine. Refer to Oil Pan Installation .

    2. 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.

  2. Install the transmission to oil pan bolts and nuts.

    3. Tighten
    Tighten the bolts to 47 N·m (34 lb ft).


    Object Number: 331034 Size: SH
  3. Install the access plugs for the oil pan rear nuts.
  4. Position the front differential carrier assembly.
  5. Install the carrier upper and lower mounting bolts and nuts (Four Wheel Drive only). Refer to Differential Carrier Assembly Replacement in Front Drive Axle.
  6. Install the inner axle shaft housing support bracket to frame washers and nuts (Four Wheel Drive only). Refer to Differential Carrier Assembly Replacement in Front Drive Axle.

    7. Object Number: 334324 Size: SH
  7. Install the transmission cover.

    8. Tighten
    Tighten the bolts to 12 N·m (106 lb in).

  8. Install the starter motor. Refer to Starter Motor Replacement in Engine Electrical.

    9. Object Number: 327996 Size: SH
  9. Install the bolt holding the bracket for the starter wiring harness and the transmission cooler pipes.

    10. Tighten
    Tighten the bolts to 12 N·m (106 lb in).

  10. Install the CKP sensor wiring harness in the retainer.
  11. Install the oil filter adapter. Refer to Oil Filter Adapter and Bypass Valve Assembly Replacement .

    12. Object Number: 48327 Size: SH
  12. Install the oil cooler pipes bracket bolt.

    13. Tighten
    Tighten the bolts to 12 N·m (106 lb in).


    Object Number: 188048 Size: SH
  13. Install the oil filter. Refer to Engine Oil and Oil Filter Replacement
  14. Install the oil pan drain plug.

    15. Tighten
    Tighten the oil pan drain plug to 25 N·m (18 lb ft).

  15. Lower the vehicle.
  16. Fill the crankcase with engine oil. Refer to Engine Oil and Oil Filter Replacement .
  17. Connect the battery negative cable. Refer to Battery Replacement in Engine Electrical.