Screws are the components that guarantee the perfect union between the Cylinder Head , the gasket and the engine block, thanks to the surface pressure they generate on the parts when they are fixed.

In older engines, its use was only with the application of torque. Due to friction losses, this method does not generate uniform tension on all screws in the Cylinder Head and requires that they be retorqued after a certain period of engine use.

Following the evolution of new generations of engines, the method of applying torque followed by tightening angle began to be used. This method, provided for in the VDI 2230 standard/script , is more precise in controlling the force applied to the Cylinder Head , generating a more uniform tension and not requiring the screws to be retorqued.

When using the torque-angle method, the bolts are plastically deformed, i.e. they are elongated so that their length no longer returns to the original dimension once they have been dismantled. Along with this elongation, there is a reduction in diameter. This reduces the strength of the bolt and puts the reliability of the joint and the sealing of the assembly at risk if it is reapplied.

Therefore, good fastening and proper sealing will only be possible if the assembly recommendations are followed as specified. Bolts that have already undergone plastic deformation must not be reapplied. Only in this way can unwanted leaks and burning of the gasket be completely avoided.