My 3Cyl. 90HP '94 90tlrs hot horn goes off at WOT. Just had water pump and thermostat replaced before any hot horn alarm. No alarm until about 10 hours after water pump. Tell tale stream is good. Engine does not feel hot when horn goes off. When I run it on the muffs, the thermostat housing at the top of the head is the only thing that feels hot(is this normal?). I plan to 1) test t-stat in hot H20 w/thermometer, 2)Check for hot spots with an infrared thermo at WOT, and as a last resort remove the head and check for plugged passages or blown head gasket or warped head. My question is this: Is this a difficult procedure to remove the head, and is this sometimes necessary to get to otherwise unaccessible water passages?