Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 257Get this manual
Cylinder Head Installation 1Install each cylinder head to engine block with thermostat pocket "UP"Apply light oil to cylinder head bolt threads and bolt faceTorque bolts 18 and 20 to 30 lbft(40.5 Nm) and rotate 90 Torque all other bolts to 20 lbft(27.0 N'm) and rotate 90 0
2Install thermostat assembly into each cylinder head3Install overheat temperature sensor into STARBOARD cylinder head opposite#1 spark plug