Seal 336493

Function and Technical Context

This seal acts as a dynamic seal in the transmission and lubrication system of outboard and inboard engines from the OMC group, sealing the passage between rotating shafts and the propulsion unit housing to prevent oil leakage and seawater ingress. Its position in areas of continuous friction makes it a critical component for maintaining the watertightness of the drive train, as any lubricant loss in that area directly exposes bearings and gears to corrosion and premature wear. A degraded seal can cause emulsification of the outboard oil, contamination of internal fluids and, in the most severe cases, a catastrophic failure of the propulsion unit that leaves the vessel immobilized in the water. The timely replacement of this low-cost component protects expensive mechanical assemblies such as the lower unit or gearbox from costly repairs.

When to Replace This Part?

The clearest signs of a deteriorated seal are the appearance of oil streaks on the water surface around the propeller shaft, an unexplained drop in lubricant level in the outboard and the presence of whitish or milky-looking oil, a clear indication that water has entered the lubrication circuit. It is recommended to inspect the condition of the seal at each seasonal maintenance interval and replace it systematically whenever the lower unit is disassembled for any other internal work, given that the cost of the part is minimal compared to the damage that a faulty seal can cause. Replacing it preventively during the annual overhaul is the standard practice among marine mechanics specializing in OMC, Johnson and Evinrude engines to prevent costly failures and unexpected immobilizations during operation.

Compatible Johnson/Evinrude Engines

Equivalent Manufacturer References