Torque-To-Yield Fasteners
Many bolts on the 3.0L V6 (L81) are "torque-to-yield" fasteners. Torque-to-yield fasteners must be replaced whenever removed and require a torque angle meter in addition to a torque wrench for proper installation. Simply put, a "torque-to-yield" fastener is designed to stretch a certain amount upon correct installation. This is why they cannot be re-used. Once stretched in position, this action cannot be repeated.
The process to use a torque angle meter tool is as follows. First, a specific torque is applied using a torque wrench. Next, a special angle of rotation(s) is applied using a torque angle meter tool. For example, the specification of 27 N.m (20 ft-lbs) +60° +30° means:
- Use a torque wrench to tighten all bolts in sequence to 27 N.m (20 ft-lbs).
- Then, use a torque angle meter to turn all bolts in sequence an additional 60 degrees.
- Finally, use a torque angle meter again to turn all bolts in sequence another 30 degrees.
Do not short-cut this sequence by tightening to specification, then turning to 90 degrees (60° + 30°) in one step. Tightening is done in steps for proper bolt stretching and clamping to take place.