Running little hot

[JohnKnsil]

I have a 1987 17.5' Bayliner Capri with Volvo AQ131 and 275 outdrive. The last two times out i notice at full throttle or if I am pulling a skier; the temp just goes slightly over safe zone temp and starts pinging. Both pumps seem to be working fine and closed system water pump is brand new last season. What else could be causing this? Or how do I troubleshoot this?

Thanks,
John