What is the sequence for tightening head bolts?
Normally you would tighten conventional head bolts in a crisscross pattern in three steps, to one-third, two-thirds, and then to the final torque. Stretch bolts are tightened in a torque-plus-angle sequence. Various engines use similar but different sequences and specification.
How do you torque head bolts?
How to tighten torque to yield bolts
- Tighten all bolts in sequence, and in two stages to a snug torque value of say, 30 Nm.
- Apply a 90 degree rotation to all bolts in the proper tightening sequence.
- Apply a further 90 degree rotation to all bolts in the proper tightening sequence.
Why the correct cylinder head bolts tightening sequence is important?
“Why is the cylinder head tightened in a correct sequence?” Because the head gasket “flows” under pressure to assume its final shape, and correct distribution of the material and relieving tensions can be ensured by the correct tightening order.
How do you set a torque wrench?
Tighten the knob at the end of the torque wrench. Turn the knob at the end of the wrench handle clockwise. This will tighten the wrench and set the level of torque on the wrench. If you need to adjust the torque again, loosen the knob and turn the handles to the torque that you need.
Why is torque sequence important?
Because the joint surfaces compress, tightening one bolt in the vicinity of another will affect the preload generated by the first bolt tightened. A good tightening sequence ensures that an even preload distribution is achieved in the joint (See Dia. A).
How do you sequence torque flange bolts?
Tightening sequence. The first pass, lightly tighten the first bolt then move directly across or 180 degrees for the second bolt, then move1/4 turn around the circle or 90 degrees for the third bolt and directly across for the fourth. Continue this sequence until all bolts are tightened.
What happens if you dont torque head bolts?
Another consequence of failing to torque the head bolts properly can be head warpage. Uneven loading created by unevenly tightened head bolts can distort the head. Over a period of time, this may cause the head to take a permanent set.