UPPER CRANKSHAFT SEAL YAMAHA 93102-36351

Function and technical context

The crankshaft upper seal is a critical component of the engine sealing system that seals the interface between the crankshaft and engine block housing. Its main function is to prevent lubrication oil leaks from the combustion chamber to the outside, maintaining the internal pressure of the lubricating system. This seal works under conditions of high rotational speed and continuous contact with the crankshaft, being especially important in Yamaha marine engines where exposure to temperature changes and load cycles are intense. A failure in this component causes progressive loss of oil, contamination of the lubrication system and, consequently, accelerated wear of bearings and increased internal friction.

When to replace this part?

Symptoms of wear include oil stains around the top of the crankshaft, a drop in the oil level between overhauls, and the presence of oily residue on the outer casing. Although there is no fixed replacement interval, it is advisable to inspect the condition of the seal during each seasonal inspection and replace it preventively when dismantling the engine or if persistent drips are observed. Replacing the seal preventively is significantly more economical than repairing damage caused by prolonged lubricant leaks.

Equivalent manufacturer part numbers