GM Service Manual Online
For 1990-2009 cars only

Light knock hot may be caused by one or more of the following conditions:

    â€¢ Loose torque converter bolts
    â€¢ Exhaust leak at the manifold (tighten the bolts, replace the gasket if necessary)
    â€¢ Excessive rod bearing clearance, (replace the bearings as necessary)
    â€¢ Detonation or spark knock, refer to Engine Controls.