GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Century 🢒 Engine 🢒 Engine Mechanical - 3.1L 🢒 Engine Replacement

Removal Procedure
  1. Disconnect the battery ground (negative) cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  2. Drain the engine coolant from the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  3. Drain the engine oil. Refer to Engine Oil and Oil Filter Replacement .
  4. Remove the throttle body air inlet duct and the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls - 3.1L.
  5. Remove the hood panel. Refer to Hood Replacement in Body Front End.
  6. Remove the engine mount struts. Refer to Engine Mount Strut Replacement .
  7. Remove the drive belt. Refer to Drive Belt Replacement .
  8. Raise and suitably support the vehicle as required. Refer to Lifting and Jacking the Vehicle in General Information. Disconnect the electrical harness connectors from the following:
    9. • 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
  9. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  10. Remove the oil filter.
  11. Remove the three-way catalytic converter pipe from the right (rear) exhaust manifold. Refer to Catalytic Converter Replacement in Engine Exhaust.
  12. Remove the engine mount lower nuts. Refer to Engine Mount Replacement .
  13. Remove the torque converter cover. Refer to Torque Converter Cover Replacement in Automatic Transaxle-4T60-E.
  14. Remove the starter motor. Refer to Starter Motor Replacement in Engine Electrical.
  15. Remove the A/C compressor. Refer to Compressor Replacement (3.1L) in HVAC. Suitably support the compressor.
  16. Remove the torque converter bolts. Refer to Flywheel to Torque Converter Bolt Replacement in Automatic Transaxle-4T60-E.
  17. Remove the right engine splash shield. Refer to Engine Splash Shield Replacement in Body Front End.
  18. Remove the transaxle brace. Refer to Transmission Brace Replacement in Automatic Transaxle-4T60-E.
  19. Disconnect the radiator outlet hose from the engine. Refer to Radiator Outlet Hose Replacement in Engine Cooling.

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

    22. 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.

  22. Disconnect the accelerator control and cruise control servo cable from the throttle body and the cable bracket. Refer to Accelerator Control Cable Replacement in Engine Controls - 3.1L and Cruise Control Cable Replacement in Cruise Control.
  23. Disconnect the vacuum hoses from the upper intake manifold.
  24. Disconnect the power brake booster vacuum hose from the upper intake manifold. Refer to Vacuum Brake Booster Hose Replacement in Hydraulic Brakes.
  25. Disconnect the fuel feed and return hoses.
  26. Remove the power steering lines from the power steering pump. Refer to Power Steering Hoses Replacement in Power Steering System.
  27. Remove the power steering pump and reposition. Refer to Power Steering Pump Replacement in Power Steering System.
  28. Disconnect the heater outlet and inlet hoses from the engine. Refer to Heater Hoses Replacement (3.1L) in HVAC.
  29. Disconnect the radiator inlet hose from the engine. Refer to Radiator Inlet Hose Replacement in Engine Cooling.
  30. Attach the engine lifting device.

    31. Object Number: 160967 Size: SH
  31. Remove the upper transaxle-to-engine bolts (3, 4 and 5) and stud (2).
  32. Remove the engine from the vehicle.
  33. Remove the flywheel. Refer to Engine Flywheel Replacement .
  34. Install the engine to the engine stand.
  35. Remove generator and generator bracket. Refer to Generator Replacement in Engine Electrical.
  36. Remove the engine mount bracket. Refer to Engine Mount Bracket Replacement .
  37. Remove the drive belt tensioner. Refer to Drive Belt Tensioner Replacement .
  38. Remove the ignition control module. Refer to Ignition Control Module Replacement in Engine Controls - 3.1L.

Installation Procedure
  1. Install the ignition control module. Refer to Ignition Control Module Replacement in Engine Controls - 3.1L.
  2. install the drive belt tensioner. Refer to Drive Belt Tensioner Replacement .
  3. install the engine mount bracket. Refer to Engine Mount Bracket Replacement .
  4. Install the generator and the generator bracket. Refer to Generator Replacement in Engine Electrical.
  5. Remove the engine from the engine stand.
  6. Install the engine to the vehicle.

    7. 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.

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

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

  8. Remove the engine lifting device.
  9. Install the power steering pump. Refer to Power Steering Pump Replacement in Power Steering System.
  10. Install the power steering lines to the power steering pump. Refer to Power Steering Hoses Replacement in Power Steering System.
  11. Connect the radiator inlet hose from the engine. Refer to Radiator Inlet Hose Replacement in Engine Cooling.
  12. Connect the heater outlet and inlet hoses to the engine. Refer to Heater Hoses Replacement (3.1L) in HVAC.
  13. Connect the fuel feed and return hoses.
  14. Connect the power brake booster vacuum hose to the upper intake manifold. Refer to Vacuum Brake Booster Hose Replacement in Hydraulic Brakes.
  15. Connect the vacuum hoses to the upper intake manifold.

    16. 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.

  16. Connect the accelerator control and cruise control servo cable to the cable bracket and the throttle body. Refer to Accelerator Control Cable Replacement in Engine Controls - 3.1L and Cruise Control Cable Replacement in Cruise Control.
  17. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  18. Connect the radiator outlet hose to the engine. Refer to Radiator Outlet Hose Replacement in Engine Cooling.

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

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

  20. Install the transaxle brace. Refer to Transmission Brace Replacement in Automatic Transaxle-4T60-E.
  21. Install the right engine splash shield. Refer to Engine Splash Shield Replacement in Body Front End.
  22. Install the torque converter bolts. Refer to Flywheel to Torque Converter Bolt Replacement in Automatic Transaxle-4T60-E.
  23. Install the A/C compressor. Refer to Compressor Replacement (3.1L) in HVAC.
  24. Install the starter motor. Refer to Starter Motor Replacement in Engine Electrical.
  25. Install the torque converter cover. Refer to Torque Converter Cover Replacement in Automatic Transaxle-4T60-E.
  26. Install the engine mount lower nuts. Refer to Engine Mount Replacement .
  27. Install the three-way catalytic converter pipe to the right (rear) exhaust manifold. Refer to Catalytic Converter Replacement in Engine Exhaust.
  28. Install the oil filter. Refer to Engine Oil and Oil Filter Replacement .
  29. Connect electrical harness connectors to the following:
    30. • 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
  30. Lower the vehicle.
  31. Install the drive belt. Refer to Drive Belt Replacement .
  32. Install the engine mount struts. Refer to Engine Mount Strut Replacement .
  33. Install the hood panel. Refer to Hood Replacement in Body Front End.
  34. Install the throttle body air inlet duct and the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls - 3.1L.
  35. Connect the battery ground (negative) cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  36. Fill the with new engine oil. Refer to Refer to Engine Oil and Oil Filter Replacement .
  37. Fill with cooling system with engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  38. Fill the power steering system with power steering fluid. Refer to Refilling the Power Steering System in Power Steering System.
  39. Check for leaks.