Mercury Mariner 4 and 5HP 4-Stroke Outboards Service Shop Manual 1999, Page 143Get this manual

CYLINDER BLOCK AND CRANKCASE
16Remove the breather cap
aScrew (2)Breather Cap

cGasket
17Remove the breather tubes and wave washers

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