GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

Important: Rotate the engine until the mark on the crankshaft balancer is at the 2 o'clock position.

Rotate the crankshaft counter clock wise 88 mm (3 1/2 inch), aligning the crankshaft balancer mark with the first lower water pump bolt, about 12:30.

This will position the engine so that no valves are close to the piston crown.


    Object Number: 358427  Size: SH
  1. Disconnect both the battery negative cables from the batteries. Refer to Battery Cable in Engine Electrical.
  2. Remove the valve rocker arm cover from the cylinder head. Refer to Valve Rocker Arm Cover Replacement .
  3. Notice: All valve train components must be reassembled in the exact order and position from which they were removed.

  4. Remove the valve rocker arm shaft bolts from the cylinder head.

  5. Object Number: 358429  Size: SH
  6. Remove the valve rocker arm shaft with the valve rocker arm.

  7. Object Number: 172998  Size: SH

    Important: The push rods must be installed in the original direction as disassembly. This is because the push rods have different degrees of hardness at each end. A paint stripe identifies the upper end of the push rod. If the paint stripe is not visible, mark the push rod on the upper end as the push rods are removed.

  8. Remove the push rods from the engine block.
  9. Remove the valve rocker arms from the cylinder head.
  10. Insert a screwdriver into the valve rocker arm shaft bore and break off the end of the nylon valve rocker arm retainers.

  11. Object Number: 66612  Size: SH
  12. Remove the valve rocker arm retainers with a pair of pliers.
  13. Slide the valve rocker arms from the rocker arm shaft.
  14. Inspect each of the valve train components. Refer to Valve Rocker Arm and Shaft Clean and Inspect .

Installation Procedure

Notice: All valve train components must be reassembled in the exact order and position from which they were removed.

Important: Lubricate the valve rocker arms with clean engine oil before installing.


    Object Number: 172998  Size: SH
  1. Install the valve rocker arms to the valve rocker arm shaft (one type of valve rocker arm is used at all locations) to the cylinder head.
  2. Install the valve rocker arm retainers to the cylinder head.
  3. Center the valve rocker arm on the corresponding holes in the valve rocker arm shaft.
  4. Use a drift of at least 13 mm (1/2 inch) in diameter to install new retainers to the valve springs.
  5. Notice: Install the valve pushrods with the copper-colored, painted, or marked end up in order to avoid damage or premature wear.

  6. Install the push rod, with the painted or marked end up to the engine block.

  7. Object Number: 358429  Size: SH

    Notice: Improper installation of the valve rocker arm shaft bolts may cause valve rocker arm shaft breakage and piston to valve contact.

  8. Install the valve rocker arm shaft assembly to the cylinder head.

  9. Object Number: 358427  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.

  10. Install the valve rocker arm shaft bolts to the cylinder head.
  11. Tighten
    Tighten the bolts to 55 N·m (40 lb ft).

  12. Install the valve rocker arm cover to the cylinder head. Refer to Valve Rocker Arm Cover Replacement
  13. .

  14. Connect both the battery negative cables to the batteries. Refer to Battery Cable in Engine Electrical.