Mercury Mariner 4, 5, and 6HP 4-Stroke Factory Service Manual, Page 153Get this manual

CYLINDER BLOCK AND CRANKCASE
16Remove the breather cap

aScrew (2)Breather CapGasket 17Remove the breather tubes and wave washers

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