Hi, I'm still pretty new here, and new to boating. My 1987 Merc 60 starts and runs excellent. When on the muffs, the water stream is very strong, lots of water and it shoots out about 15 feet, and just luke warm. When I put it on the water and operate at slow speeds, the water coming out the pee valve is a bit warmer as expected, however when I ask her to go about 35 or 40 mph for perhaps 2 minutes, the water is hot to me. I looked in the lower unit myself and the impeller looks brand new. Took it to a Merc mechanic (supposed to be the best Merc guy in town), he replaced the water pump and said the plugs were incorrect - replaced those as well. He gave it back and said it's good to go. Took my meat thermometer with me on the next test run, and when we run it at 35 or 40 mph, the water temp coming out gets up to 140 f degrees. As soon as we slow it down to slower speeds, the temp drops down 20 or more degrees. Is the 140 at higher speeds ok? This runabout will be used to pull a tuber, so it needs to be able to perform. Does it sound ok?
