"Manny, I have a 70 HP on a fl
"Manny, I have a 70 HP on a flounder boat that we bought used. The motor temp alarm would come on running at full speed, but the water out of the by-pass hose was not hot. After replacing the water pump impeller, we still had the same problem. The Tohatsu dealer told me to pull the head and clean out the water jacket. I pulled the head and there was a build up hard fungus type of stuff that had bridged the block and the cyl. in places. I cleaned this out and the engin ran great with no more problems. Perhaps the by-pass tube on the top cyl. is stopped up from a similar type problem. Pat Muckelroy"