GM 6.5L V8 – Camshaft and Injection Pump Timing Check

1. Rotate the crankshaft to the 0 degrees TDC position.
2. Remove the oil fill pipe and grommet.
3. Inspect the position on the injection pump driven gear:
• If the alignment slot is at the 6 o’clock position, go to step 4.
• If the alignment slot is at the 12 o’clock position, rotate the crankshaft one revolution and go to step 4.
4. Remove the water pump assembly.
5. Inspect that the alignment marks of the injection pump drive and driven gears are next to each other (see
Figure 2-41, view A).
6. Remove the injection pump driven gear from the drive shaft of the injection pump.
7. Rotate the crankshaft one revolution (in a clockwise direction) to the 0 degrees TDC position and remove the
torsional damper and front cover.
8. Remove the injection pump drive gear from the front of the camshaft.

9. Inspect that the aliqnment marks of the crankshaft and camshaft sprockets are next to each other (see Figure
2-41, view B).
10. Check the tension of the timing chain:
• Install a dial indicator so that its plunger tip contacts the outside of the timing chain at a midpoint between the crankshaft and camshaft sprockets on the right side of the engine.
• At the location of the dial indicator plunger contact, move the timing chain toward the center of the engine and align the dial indicator needle with zero (see Figure 2-42, view A).
• Move the timing chain away from the center of the engine and observe the total dial indicator needle travel (see Figure 2-42, view B):
– If measured travel is within the following specifications, go to step 10:
– Less than 12.7 mm (0.500 in.) for a new chain
– Less than 20.3 mm (0.800 in.) for a used chain
– If measured travel is not within the specifications, replace the timing chain and sprockets.

11. Remove the timing chain and sprockets, check the following items and make any necessary corrections:
• Alignment mark on the crankshaft sprocket in the 12 o ’clock position
• Key and keyway of the crankshaft with no damage
• Alignment mark on the camshaft sprocket in the 6 o ’clock position
• Alignment dowel of the camshaft with no damage
12. Install the timing chain and sprockets and rotate the crankshaft one revolution (in a clockwise direction) to the 0 degrees TDC position.
13. Install the injection pump drive and driven gears with aligned marks.
14. Install the front cover, torsional damper, water pump assembly and oil fill pipe.

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