What is the sequence for tightening the head bolts?
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These head bolts need to be tightened in a very different fashion. 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.
Do you have to remove head bolts in a sequence?
These bolts connect the cylinder head to the engine block through the head gasket. As such, you must remove (and later reinstall) the head bolts in the proper sequence to avoid damage to the cylinder head. Head bolts ensure a proper seal between the cylinder head and the engine block.
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.
What can cause a cylinder head to warp?
Overheating is the most common cause of cylinder head warping and cracking. When an engine gets too hot, the cylinder head often bears the brunt of the pain. This causes the components to warp and pressure to leak.
What is a typical cylinder head tightening sequence?
For example, a typical cylinder head tightening sequence might look like this-. 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.
How to tighten torque to yield bolts?
How to tighten torque to yield bolts 1 Tighten all bolts in sequence, and in two stages to a snug torque value of say, 30 Nm 2 Apply a 90 degree rotation to all bolts in the proper tightening sequence 3 Apply a further 90 degree rotation to all bolts in the proper tightening sequence
Why do we tighten bolts in degrees of rotation?
Essentially, tightening bolts in degrees of rotation largely eliminates the effects of friction between threads and the bearing surface between the head of the bolt and the bearing washer.
What causes a cylinder head bolt to fail?
Therefore, if the specified preload is not applied to all the cylinder head bolts equally, it is almost certain that one or more issues such as fatigue failures of one or more bolts can occur, or vibration can cause one or more bolts to loosen themselves, leading to a failure of the joint.