ZR6 over heating but manifolds are cooled, circulator pump?

[hjelmjw11]

This is my first prom with fresh water cooling, but it is overheating at higher speeds but cools at idle. We have already taken and cleaned the heat exchanger, transmission cooler, and it has a new impeller in the raw water pump. Its not a water issue flow becuase when it is hot or idling the manifolds are being cooled and I can leave my hand on any part of the manifolds. It looks like the coolant isn't getting passed through the block and the only thing that can do that is the circulating pump, correct? I am hesitant to believe that becuase Pacific Nautiques says those rarely go out, and the other PCM dealer in Seattle said they have never even had to order one before... As if our summer here in the NW hasn't been ****ty enough already!

[j2nh]

Thermostat?

[HS]

haven't had this happen, but have been told if you see it overheat, to check the fresh water flush cap to make sure it is tight (silver cap on the transom).

[hjelmjw11]

t-stat is new...