Tick noise Coming From Inside Engine - keywords 3.5 3.5L 3.9 3.9L bent block drive LZE LZ4 LZ9 oil pump RPM shaft speed

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

Important: The information contained in this document only applies to the above described vehicles with engines produced at the Tonawanda Engine Plant. Engines produced at the Ramos Engine Plant are not involved.

Some owners may comment about a tick type noise coming from the engine compartment. Upon inspection you may find that the noise sounds like it's coming from the inside of the engine.

Some engines produced at the Tonawanda Engine Plant may have a "slightly bent" oil pump drive shaft. If the drive shaft is slightly bent it may be intermittently contacting the inside of the engine block as it rotates. The resulting contact may sound like a ticking that varies with engine speed.

Using a stethoscope type tool, attempt to hear the sound at the oil pump drive located on the top of the engine block. If the sound appears to be coming from the oil pump drive area it will be necessary to remove the oil pan and oil pump for further inspection. Once the oil pump has been removed, separate the drive shaft from the pump and inspect the shaft for straightness. If replacement is necessary, replace the shaft using the part number currently available from GMSPO.

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.