1986+ Mercury 6/8/9.9/10/15HP 2-stroke Factory Service Manual, Page 172Get this manual

POWERHEAD
It is recommended that all seals be replaced as standard rebuilding procedure

aTop crankshaft sealBottom crankshaft seal

Bearings

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives