Can a torque wrench be used to tighten head bolts?
One of the most common misconceptions about using a torque wrench to tighten head bolts is that the torque reading on the wrench indicates how much load is on each bolt. The reading on the wrench only tells you how much twisting force is being applied on each bolt.
Why is it important to tighten head bolts on gaskets?
This is especially important with gasketed surfaces because the gaskets have a certain amount of give that must be overcome by the fasteners to maintain a tight seal. When you tighten a head bolt, the force exerted by the wrench is accomplishing two things.
What happens when a head bolt is stretched too far?
This is the point where the bolt can stretch no further without being permanently deformed. Like a rubber band, a head bolt under load will stretch and spring back to its original length when the load is released. But if stretched too far, the bolt will either become permanently elongated or break.
What should head bolts be lubricated with before installation?
As a rule, the threads and underside of the head on most standard automotive head bolts should be lubricated with motor oil before the bolts are installed. The torque values specified by the engine manufacturer are typically based on oiled threads and fasteners – not dry fasteners.
One of the most common misconceptions about using a torque wrench to tighten head bolts is that the torque reading on the wrench indicates how much load is on each bolt. The reading on the wrench only tells you how much twisting force is being applied on each bolt.
This is especially important with gasketed surfaces because the gaskets have a certain amount of give that must be overcome by the fasteners to maintain a tight seal. When you tighten a head bolt, the force exerted by the wrench is accomplishing two things.
As a rule, the threads and underside of the head on most standard automotive head bolts should be lubricated with motor oil before the bolts are installed. The torque values specified by the engine manufacturer are typically based on oiled threads and fasteners – not dry fasteners.
This is the point where the bolt can stretch no further without being permanently deformed. Like a rubber band, a head bolt under load will stretch and spring back to its original length when the load is released. But if stretched too far, the bolt will either become permanently elongated or break.