GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Century (China) (CNG) 🢒 Engine 🢒 Engine Mechanical - 3.0L (L46) 🢒 Engine Replacement

Removal Procedure
  1. Disconnect the battery ground (negative) cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  2. Remove the hood panel. Refer to Hood Replacement in Body Front End.
  3. Drain the engine coolant from the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  4. Remove the throttle body air inlet duct. Refer to Throttle Body Assembly Replacement in Engine Controls - 3.0L.
  5. Remove the engine mount struts. Refer to Engine Mount Strut Replacement .
  6. Disconnect the electrical harness connectors from the following:
    7. • The knock sensor
    • The heated oxygen sensor
    • The camshaft position sensor
    • The crankshaft position sensor
    • The manifold air pressure (MAP) sensor
    • The exhaust gas recirculation (EGR) valve
    • The evaporative emissions canister purge solenoid valve
    • The throttle position (TP) sensor
    • The idle air control (IAC) valve
    • The starter motor
    • The A/C compressor
    • The generator
    • The ignition coil
    • The wiring harness grounds
    • The two body wiring harness-to-engine harness connectors
  7. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  8. Drain the engine oil. Refer to Engine Oil and Oil Filter Replacement .
  9. Disconnect the exhaust resonator pipe from the right (rear) exhaust manifold. Refer to Resonator Replacement in Engine Exhaust.
  10. Remove the engine mount lower nuts. Refer to Engine Mount Replacement .
  11. Remove the torque converter cover. Refer to Torque Converter Cover Replacement in Automatic Transaxle - 4T65-E.
  12. Remove the starter motor. Refer to Starter Motor Replacement in Engine Electrical.
  13. Remove the torque converter bolts. Refer to Flywheel to Torque Converter Bolt Replacement in Automatic Transaxle - 4T65-E.
  14. Remove the transaxle brace. Refer to Transmission Brace Replacement in Automatic Transaxle - 4T65-E.

    15. Object Number: 160967 Size: SH
  15. Remove the lower transaxle-to-engine bolt (6) and stud (1).
  16. Lower the vehicle.

    17. Caution: In order to avoid possible injury or vehicle damage, always replace the accelerator control cable with a NEW cable whenever you remove the engine from the vehicle.

    In order to avoid cruise control cable damage, position the cable out of the way while you remove or install the engine. Do not pry or lean against the cruise control cable and do not kink the cable. You must replace a damaged cable.

  17. Disconnect the accelerator control and cruise control servo cable from the throttle body and the cable bracket. Refer to Engine Controls.
  18. Disconnect the vacuum hoses from the upper intake manifold.
  19. Disconnect the power brake booster vacuum hose from the upper intake manifold. Refer to Vacuum Brake Booster Hose Replacement in Hydraulic Brakes.
  20. Disconnect the fuel feed and return hoses. Refer to Engine Controls - 3.0L.
  21. Remove the power steering pump pulley. Refer to Power Steering Gear and Pump.
  22. Remove the power steering pump and set aside. Refer to Power Steering Gear and Pump.
  23. Disconnect the heater outlet and inlet hoses from the engine. Refer to HVAC.
  24. Disconnect the radiator inlet hose from the engine. Refer to Radiator Inlet Hose Replacement in Engine Cooling.
  25. Disconnect the radiator outlet hose from the engine. Refer to Radiator Outlet Hose Replacement in Engine Cooling.
  26. Remove the A/C compressor bolts and move the compressor aside. Refer to HVAC.
  27. Suitably support the transaxle with floor stands.
  28. Attach the engine lifting device.

    29. Object Number: 160967 Size: SH
  29. Remove the upper transaxle-to-engine bolts (3, 4 and 5) and stud (2).
  30. Remove the engine from the vehicle.

Installation Procedure
  1. Install the engine to the vehicle.

    2. Object Number: 160967 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.

  2. Install the upper transaxle-to-engine bolts (3, 4 and 5) and stud (2).

    3. Tighten
    Tighten the upper transaxle-to-engine bolts (3, 4 and 5) and stud (2) to 75 N·m (55 lb ft).

  3. Remove the engine lifting device.
  4. Remove the floor stands from the transaxle.
  5. Install the A/C compressor. Refer to HVAC.
  6. Connect the radiator outlet hose from the engine. Refer to Radiator Outlet Hose Replacement in Engine Cooling.
  7. Connect the radiator inlet hose from the engine. Refer to Radiator Inlet Hose Replacement in Engine Cooling.
  8. Connect the heater outlet and inlet hoses to the engine. Refer to HVAC.
  9. Position the power steering pump. Refer to Power Steering Gear and Pump.
  10. Install the power steering pump. Refer to Power Steering Gear and Pump.
  11. Install the power steering pump pulley. Refer to Power Steering Gear and Pump.
  12. Connect the fuel feed and return hoses. Refer to Engine Controls - 3.0L.
  13. Connect the power brake booster vacuum hose to the upper intake manifold. Refer to Vacuum Brake Booster Hose Replacement in Hydraulic Brakes.
  14. Connect the vacuum hoses from the upper intake manifold.

    15. Caution: In order to avoid possible injury or vehicle damage, always replace the accelerator control cable with a NEW cable whenever you remove the engine from the vehicle.

    In order to avoid cruise control cable damage, position the cable out of the way while you remove or install the engine. Do not pry or lean against the cruise control cable and do not kink the cable. You must replace a damaged cable.

  15. Connect the accelerator control and cruise control servo cable to the cable bracket and the throttle body. Refer to Engine Controls - 3.0L.
  16. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

    17. Object Number: 160967 Size: SH
  17. Install the lower transaxle-to-engine bolt (6) and stud (1).

    18. Tighten
    Tighten the upper transaxle-to-engine bolt (6) and stud (1) to 75 N·m (55 lb ft).

  18. Install the transaxle brace. Refer to Transmission Brace Replacement in Automatic Transaxle - 4T65-E.
  19. Install the torque converter bolts. Refer to Flywheel to Torque Converter Bolt Replacement in Automatic Transaxle - 4T65-E.
  20. Install the starter motor. Refer to Starter Motor Replacement in Engine Electrical.
  21. Install the torque converter cover. Refer to Torque Converter Cover Replacement in Automatic Transaxle - 4T65-E.
  22. Install the engine mount lower nuts. Refer to Engine Mount Replacement .
  23. Connect the resonator pipe to the right (rear) exhaust manifold. Refer to Resonator Replacement in Engine Exhaust.
  24. Lower the vehicle.
  25. Connect electrical harness connectors to the following:
    26. • The knock sensor
    • The heated oxygen sensor
    • The camshaft position sensor
    • The crankshaft position sensor
    • The manifold air pressure (MAP) sensor
    • The exhaust gas recirculation (EGR) valve
    • The evaporative emissions canister purge solenoid valve
    • The throttle position (TP) sensor
    • The idle air control (IAC) valve
    • The starter motor
    • The A/C compressor
    • The generator
    • The ignition coil
    • The wiring harness grounds
    • The two body wiring harness-to-engine harness connectors
  26. Fill the with new engine oil. Refer to Refer to Engine Oil and Oil Filter Replacement .
  27. Install the engine mount struts. Refer to Engine Mount Strut Replacement .
  28. Install the throttle body air inlet duct. Refer to Throttle Body Assembly Replacement in Engine Controls - 3.0L.
  29. Install the hood panel. Refer to Hood Replacement in Body Front End.
  30. Fill with cooling system with engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  31. Connect the battery ground (negative) cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.