Manufacturer communication — 2006 GMC YUKON DENALI XL

• Applies to GM passenger cars and trucks, model years 2000 to 2024.

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  GM Passenger Cars and Trucks 2000 2024

• Some technicians may be replacing engines instead of repairing them and replacing worn components as needed.

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  Some technicians may be replacing engines instead of repairing and replacing worn components as needed.

Possible causes

• The wear may be caused by the vehicle duty cycle, dust in the operating environment and local fuel quality.

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  These conditions may be caused by the vehicle duty cycle, dust in the environment the vehicle is being operated in and local fuel quality.

Steps to confirm (in the document’s order)

1. Cylinder wall scratch: if a pick or fingernail cannot catch on it, the cylinder bore/engine block does not require replacement.

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   In this example, if you cannot catch a pick or fingernail on the scratch, the cylinder bore/engine block does not require replacement.

2. With a scored piston, inspect for broken and/or stuck rings, and inspect the ring lands and cylinder wall for damage.

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   In this example, inspect for broken and/or stuck rings and piston ring lands and cylinder wall for damage.

3. When bearing failure is suspected, remove the oil filter and inspect it for excessive debris and damaged pleats.

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   In cases involving suspected bearing failure, remove and inspect the oil filter for excessive debris and damaged pleats.

4. Minimal amounts of metal particles on the oil filter pleats should not pose a concern.

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   In this example, minimal amounts of metal particles are visible on oil filter pleats and should not pose a concern.

5. Excessive metal particles or damaged filter pleats mean unfiltered oil with bearing debris may have been pumped into the oil galleries throughout the engine.

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   If excessive amounts of metal particles are observed, or if there is evidence of damaged oil filter pleats, then unfiltered oil with bearing debris may have been pumped into the oil lubrication galleries throughout the engine.

Repair

1. Minor scratching/scoring on camshaft lobes and/or camshaft bearing journals: the scored components can be replaced without replacing the engine assembly.

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   Example of minor scratching/scoring visible on camshaft lobes and/or camshaft bearing journals. In this example, the scored components can be replaced without need for engine assembly replacement.

2. Minor scratching/scoring on connecting rod bearings: the scored components can be replaced without replacing the engine assembly.

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   Example of minor scratching/scoring visible on connecting rod bearings. In this example, the scored components can be replaced without need for engine assembly replacement.

3. A slightly scored piston can be replaced without replacing the engine assembly.

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   If the piston is slightly scored, the scored piston can be replaced without need for engine assembly replacement.

Caution

• If inspection reveals cylinder wall damage (excessive scoring or out-of-round), an engine replacement may be required.

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  cylinder bores and reveals cylinder wall damage (i.e. excessive scoring or out-of-round), an engine replacement may be required.