Impeller replaced, boat still overheating...

2004 Wakesetter 23LSV, 170 hours, never had a problem until today. Launched, idled for a bit getting out of the wakeless zone, started overheating (hit about 180 degrees). Shut it off, removed the old impeller, found that it had disintegrated. Had a new one in the glove compartment, installed it easily, and then ran the boat for the next 4 hours with no problems. Wakeboarded, surfed, pulled a slalom skier for 10 minutes, swam, etc. Coming back into the launch ramp we were pulling another slalom skier and the temp jumped to 180 again, boat idled down into "safe mode", but if left at idle it would come back down to 160 and hold steady there. Anything above idle the temp would start to climb. So we loaded it up and came home. Pulled the new impeller cover off; it looks fine. Pulled the thermostat off; there was a TINY chunk of impeller near the thermostat, but not big enough to plug anything up substantially. I bought a new 160 degree thermostat at NAPA just in case the old one coincidentally went bad today, and I am replacing it now. Any thoughts as to why I am overheating, other than a bad thermostat?

there probably more pcs in the cooler. most likely it is. Kenny

Thanks Kenny; you were right. My tranny oil cooler is downstream from the impeller, so I unhooked the water line there and pulled out a big handful of impeller pieces stuck in the tranny oil cooler screen. This is almost certainly the source of my problems. I replaced the thermostat anyway since I already had it apart, but I tested my stat later on the stove and it opened up at about 160-180. I guess I can keep it for a spare...Thanks again. I should have looked at the cooler first; I didn't realize there was a screen in-line there.

no problem, im more then happy to help people out =). Kenny.