ok this may be a hard question to answer...i have a 1987 johnson 150....my temp guage doesnt have numbers...just "c" on the left and "h" on the right...looks like a fuel guage sort of...with the ears hooked up my temp goes to about 3/4 then drops to about 5/8 before leveling off...is that ok? how can i tell the exact temp? what should the temp be?