Lower End Engine Knock Noise - keywords pin piston rod

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

The customer concern may be an engine knock noise heard at all times.

This concern has been occurring on low mileage engines.

Engineering is interested in any 2005 8.1 low mileage engine knock noises.

This engine noise may be described as a piston, piston rod, or wrist pin type noise. This noise will be excessive and is not to be confused with cold start tick noises that go away when the engine warms up. This piston type noise may be caused by a piston pin that has come loose or moved in the piston bore.

Remove the accessory drive belt and cancel cylinders to verify a lower engine knock noise.

If the dealer has verified a lower end engine knock noise, regardless of engine speed, please do not attempt repairs.

The engine will need to be replaced for a lower end knock noise.

All 2005 8.1 engines will be requested and returned for the engineering investigation.

All other engine noises should be diagnosed using current SI diagnostics.

Note: 8.1 engine replacement ordering procedures will change depending on its application. Medium duty dealers are to order the engine with a SPAC case and a CS03 priority order. Light duty dealers have two different engine ordering procedures depending on mileage. If the engine has 250 miles or less, use PI number AIP3096 for contacting General Motors Technical Assistance.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.