Hey guys, I have a Baja 405 with twin 496HOs. Ive had a couple of incidents when I start up and warm at idle and get an overheat alarm. I check the risers and they were a bit hot. So, I went through the whole cooling system and absolutely nothing. Impeller is perfect (new), no blockage anywhere, etc... what I noted is that it NEVER has an issue with the fresh water flush (located just before the impeller). ONLY happens when I’m sitting at the dock. The only thing before the flush unit is the transom hose passthru which is clean. The risers and manifolds are clean, sensors are in good order...
So, i dropped it off at my favorite mechanic’s and after a few checks, he claims it has to be the fresh water flush ball valve - which he says needs about 1000-1200 RPMs for 20-30 seconds to pull open the ball. I’ve heard this before, but never had to do this.

Anyone else have this experience/thoughts? Do we really need to push the RPMs up to open the valve?

Thanks for help!