Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 272Get this manual
POWERHEAD
CYLINDER HEAD INSTALLATION
1Install each cylinder head to engine block with thermostat pocket "UP"Apply light oil to cylinder head bolt threads and torque bolts to 30 Ibft(41 Nm) then turn an additional 902Install thermostat assembly into each cylinder head3Install overheat temperature sensor into STARBOARD cylinder head below #1 spark plug