YAMAHA CYLINDER HEAD SCREW 90105-08046-00

Function and technical context

This screw is part of the cylinder head fixing assembly on Yamaha engines, being responsible for maintaining a tight and structurally sound connection between the cylinder head and the engine block. The cylinder head houses the distribution, injection and ignition systems, so its fastening must be precise and uniform to guarantee the tightness of the combustion chambers. Poor tightening or corrosion of the screw can cause cooling water leaks, loss of compression, moisture infiltration into the crankcase and, in extreme cases, engine overheating during navigation.

When to replace this part?

Cylinder head bolts should be inspected regularly at each seasonal maintenance, especially in saline environments where corrosion progresses rapidly. Symptoms such as coolant leaks around the head gasket, abnormal engine overheating, or difficulty starting may indicate looseness or deterioration in the fastening points. It is recommended to preventively replace any screw that shows signs of oxidation, pitting corrosion or deformation, since a failure in navigation can leave the boat without propulsion far from port.

Equivalent manufacturer part numbers