Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 243Get this manual
NOTE: BE SURE that water in thermostat tester is allowed to cool sufficiently [below 110 (43 C)] before testing the other thermostat A torque wrench is essential for correct reassembly of powerheadDO NOT attempt to reassemble powerhead without using torque wrenchAttaching bolts for covers, housings and cylinder heads MUST BE torqued by tightening bolts in progressive steps (following specified torque sequence) until specified torque is reached (see "Example," following)EXAMPLE: If cylinder head attaching bolts require torque of 20 lbft(27.0 Nm)a) tighten all bolts to lbft(7.0 Nm), following specified torque sequence, b) tighten all bolts to 10 lbft(13.5 Nm)following torque sequence, then finally c) tighten all bolts to 20 lbft(27.0 N'm), following torque sequence
IMPORTANT: DO NOT operate engine without thermostats installed