I have twin 470s and they show that they are running hot on the gauge but measured with a lazer shows running at 160 or less at the reservior and all points on the engine. Have changed out the thermostat and the temp sender and now it reads even higher on the gauge on the port engine, have yet to change sender on stbd side. Gauge pegs when grounded like it should on port havent checked the stbd side. Thinking that either the gauge is bad as they set halfway when switch is off or I have the wrong senders. Again temps look fine at all the points to measure(exhaust elbow,reservior, heat exchanger, all hoses, block, and head,)and waterpump is new on both engines. Has anyone ever ran into this problem before?. The boat is a 1977 240 SDA Srv Sundancer with twin 470s that run perfect except for this, any help would be appreciated.