Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 258Get this manual

POWERHEAD
NOTE: BE SURE that water in thermostat tester is allowed to cool sufficiently [below 130 (56 C)] before testing the other thermostat

Powerhead Reassembly and Installation

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