WASHER 90201-46M29 REC90201-46M29

Function and technical context

This washer is part of the fastening and sealing system in Yamaha engines, acting as a load distribution element under the heads of critical screws and nuts. Its function is to prevent the fastening elements from becoming embedded in the aluminum or base material surfaces of the engine, which could compromise the tightness of adjacent gaskets and seals. Working in high vibration systems such as marine engines, it guarantees that the clamping pressure is distributed evenly, preventing microleaks of coolant, oil or seawater that could lead to accelerated corrosion or premature failure of attached components.

When to replace this part?

Washers should be inspected during each seasonal maintenance check and replaced if they show permanent deformation, active corrosion, or tear marks around the perimeter. Although they do not have a fixed replacement interval like impellers or belts, preventive replacement during engine repairs is standard practice among professional mechanics, as its cost is minimal compared to repairs that can arise from poor load distribution. Especially in engines that have been idle or exposed to a saline environment, checking the condition of washers at critical cooling and sealing points avoids costly navigation problems.

Equivalent manufacturer part numbers