temp going up.

[thunder]

I was wondering if anyone has had this problem. I have a 1999 350 merc. 300 hp mag. freshwater cooled. The temp norm is 175 when hot. After you run the boat at 3000 rpms for a short time and then go down to1500 rpms or close the tenp will go up to 180-190. It will also spit some antifreeze from the cap sometimes. I have changed the thermostat. That was not it. Not sure where to go next. Thanks for any help.

[thunder]

anyone?

[TDuffy35]

I'd look at the impeller/water pump, then the heat exchanger and then the exhaust risers.

sounds like a restriction in the water flow...