Note: To perform this procedure, you must have a proprietary camshaft locking tool GM4J-44221 or its equivalent
Removal
Note: Do not turn the crankshaft after removing the camshaft sprocket, as this may result in incorrect valve timing and engine failure.
1. Remove the valve cover (see subsection 4). Also remove the spark plugs (this will make it easier to rotate the crankshaft; see chapter 1).
2. Turn the crankshaft so that the sprocket mark aligns with the dark link of the drive chain (see illustration), as well as the location of the grooves at the top of the camshaft shanks (see illustration 7.12).
8.2. Before removing the sprockets, it is necessary to align the valve timing marks
3. Perform the operations as described in paragraphs 4 and 5 of subsection 7, unscrew the fastening bolts and carefully remove the sprockets from the camshafts.
Caution: do not remove the chain from the camshaft sprockets - hang the sprockets and chain so that the lower part of the chain does not jump off the crankshaft sprocket.
4. Ensure that the camshaft caps are marked and, if necessary, mark them with paint to ensure that the caps are returned to their original locations during subsequent assembly.
5. Unscrew and remove the camshaft cover bolts in several steps. Remove the camshafts. Store the shafts separately to prevent confusion with them. If necessary, remove the rocker arms and hydraulic lash compensators. If the removed parts are intended to be used later, also store them separately, since they too must be installed in the appropriate original locations during subsequent assembly.
Inspection
6. After removing the camshafts, clean them with solvent, dry them and inspect them for the following damage.
- A) Production of metal on the necks.
- b) Thermal damage, metal wear, chipping, pitting, or uneven wear on the cams.
- With) Damage to sprocket locating pin grooves.
- d) Thread damage.
7. Assess the degree of wear and deviation from the round shape of the camshaft journals by taking measurements with a micrometer.
Installation
8. If necessary, immerse in clean engine oil and install the rocker arms and lash adjusters in their respective original locations.
9. Coat the camshaft completely with clean engine oil. Place the camshaft in the appropriate original location in the cylinder head.
10. Install the camshaft locking device.
11. Install all camshaft caps in their original locations and finger tighten them.
12. Starting at the center members and working outward, tighten the camshaft caps to the required torque.
13. Remove the locking device.
14. Place the sprockets on the camshafts and tighten the bolts to the required torque.
15. Using the socket on the extension arm, rotate the crankshaft 720° (two full turns) and check the alignment of the sprockets with the chain. The dark links should be aligned with the star marks (see illustration 8.2). If resistance is felt when turning the crankshaft, stop rotating immediately and determine the cause of the problem.
16. Install spark plugs (Chapter 1) and valve cover (subsection 4).