UPPER CRANKSHAFT SEAL YAMAHA 93102-36351

Function and technical context

The upper crankshaft seal is a critical component of the engine's sealing system, sealing the point where the crankshaft passes through the cylinder head into the timing belt. Its function is to prevent engine oil leaks from the combustion chamber to the outside, maintaining internal lubrication pressure and protecting adjacent components from corrosion. In Yamaha marine engines, this seal works under conditions of variable temperature and pressure, especially in high-demand navigation, where its deterioration can allow salt water and humidity to enter critical engine circuits.

When to replace this part?

Symptoms of upper seal wear include oil stains around the crankshaft, abnormal presence of oil on the timing covers, or visible drips on the upper area of the engine during operation. This type of seal must be inspected at each seasonal inspection and replaced preventively every 5-7 years or when loss of tightness is evident, since a degraded seal not only causes loss of lubricant but also facilitates contamination by seawater, which accelerates internal wear of the engine and can cause costly breakdowns in navigation.

Equivalent manufacturer part numbers