i have a mercury 1987 150 xr4 i put a new impeller and gaskests in lower end and new thermostats at full speed have over 15 psi and 5 to 7 at ideal temp gauge sits in 1/2 to 3/4 on temp gauge only has a c and h now when you start boat i have a beeeeeeeeeee that doesnt stop going off was a hole...