YAMAHA VERTICAL SHAFT UPPER SEAL 93106-18M01

Function and technical context

The upper vertical shaft seal is a critical component in the marine transmission of Yamaha engines that seals the interface between the propeller shaft and the engine casing, preventing salt water from entering the internal cavities of the drive unit. This seal works under extreme conditions of hydrodynamic pressure and constant contact with the marine environment, protecting itself from corrosion and erosion from turbulent flow around the shaft. Its failure allows water infiltration into the bearings and lubrication surfaces, causing accelerated oxidation, seizure of the vertical axis and total loss of propulsion capacity.

When to replace this part?

Symptoms of top seal wear include visible water leaks where the shaft meets the housing, accelerated corrosion in adjacent shaft components, and abnormal noises or excessive vibration during navigation. It is recommended to check the condition of the seal during each seasonal maintenance, especially after long navigations in salt water or after prolonged periods of non-use. Preventative replacement of the retainer, along with other vertical shaft seals, prevents costly emergency repairs at sea and prolongs engine life.

Equivalent manufacturer part numbers