GM Service Manual Online
For 1990-2009 cars only

Heavy knock hot with torque applied may be caused by one or more of the following conditions:

    • Broken balancer or pulley hub (replace parts as necessary)
    • Loose torque converter bolts
    • Accessory belts too tight (adjust the tension to specifications)
    • Accessory belts nicked (replace as necessary)
    • Exhaust system grounded (reposition the exhaust as necessary)
    • Flywheel cracked
    • Excessive main bearing clearance (replace as necessary)
    • Excessive rod bearing clearance (replace as necessary)
    • Low quality fuel