Cylinder Head Bolt Tightening Tips

Once nearly all the parts for car engines were made from heavy cast iron - such material was a great deal stronger and more immovable than the many alloys that are used today. It took longer for the heat of the engine to affect it, and when it did expand or contract the different parts moved the same distance and all together.

These days there are many different kinds of metal and even plastics that go to make up the different components of the car engine. These all have different rates of expansion and contraction as the engine heats and cools them. While using such metals gives a lighter engine more suited to today's need for speed, there is the danger of warping when one part heats up and expands faster or more slowly than the part it is bolted to.

This problem is overcome by using torque to yield bolts that have the ability to stretch while still holding all the parts in their correct place and at the correct strength. Such cylinder head bolts must be tightened carefully with special tools so that the same amount of pressure or load is gained from each bolt.

Tightening each bolt to the maximum torque as you put it into place is not the way to achieve this. Rather, you need to tighten each one just a little in turn so that the load is distributed evenly. Then you have to do the rounds of tightening a second time, taking each bolt just a little further. Finally the last tightening should be done, with the angles and amount of tightening being measured carefully each time.

In this way the bolts will each bear the same load and no warping will occur when the engine parts heat up or cool off. Such bolts are quite expensive, but necessary if the engine of the car is not to develop some major problem that will cost a great deal more than the bolts ever did.