1998+ Mercury Mariner 25HP Bigfoot Service Manual, Page 323Get this manual

POWER TRIM
Disassembly
Shock Rod Removal
IMPORTANT: Power trim system is pressurizedOutboard must be in the full "UP" position (trim rod fully extended) prior to filldrain plug, or manual release valve removala -

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