i have a 1999 glastron 175sx with a volvo penta 3.0, 4 cyl, 135 hp. I/O. the boat was used for one season new, garaged for 3 years, and ive owned it for 3 months. at idle or a little above, the temp reads 175 degrees. when you gas it and get on plane, just running around 21 mph, and 3200 rpm...