So my summer season I have been chasing an over temp situation on my port exhaust riser and I am really at the end here. I have taken the entire fresh water cooling system apart multiple times, checked for blockages, checked the brand new impeller on the brand new Sherwood raw water pump and all the vanes are intact. I swapped the elbows on the exhaust to see if the riser was bad and my problem migrated to the starboard side when the port riser went over there so I got a new one and placed it on the port manifold. New thermostat, new gaskets all the way around and here is where I stand as of my water run yesterday. On the trailer at idle sucking water out of a bucket the boat can idle for damn near an hour and the temps are the same port to starboard. Water flow out the back fills the buckets equally. Take it out on the lake to have unlimited water and give it some more throttle and the port riser temp shoots up to around 205 degrees while the starboard remains around 110-115 and cool to the touch. Both manifolds themselves are cool to the touch, only the elbow gets hot and then everything downstream from there is hot as well. The whole time the engine is under 160 degrees at the hottest temperature too.

What am I missing? The only thing I can think of trying now is opening that passageway between the manifold and the elbow that is intentionally blocked off by the gasket to in effect get more water to flow through the port side than the starboard side or placing a small restriction in the water line coming out of the starboard side of the thermostat housing to accomplish the same thing.