My 200 E-Tec H.O. E200DHXSC #5214893 started running hot last week, but only occasionally. The HOT light would come on, but the gauge still showed 140. I would shut her off, turn it on again, problem went away, gauge would drop even more on plane, for a week. Now its back and its hot on the gauge and the light. Won't even get out of the marina and she's hot.
Hooked up the laptop, while idling, the Strb. bank climbs up to 90 Celcius in 5 minutes or so, Port bank stays around 85 degrees. (gotta figure out how to set it to Fahrenheit to match the dash gauges). EMM temp stays around 60.C.
330 hrs, so I replace the impellers on both motors. They looked good and clean. Blew out the cooling lines to EMM and fuel canister, nothing in them. Cleaned out the T-stats, and by-pass, no dirt to be found.
Put it back in the water, no change.
Pull the lower unit off again, stuck a hose down the T-stat holes to flush the gremlin out, put a bucket under the engine to catch the little rat, nothing yet. Little bit of brown slime, if that. Replaced the impeller plate, gasket and seals and bolted the pump back together real carefully again tonight, left some D-Con under the cowling to get whatever is messing with my motor. Any thoughts, suggestions?

Walter