Need help, overheating at cruise rpm

midnightrider1818

Petty Officer 2nd Class
Joined
Aug 17, 2009
Messages
189
So, i have a 85 searay 250, mercruiser 260 350 with a alpha one gen one, last year at the end of the season I started to overheat at cruise, i came back in and all fine, boat sat in well for probably 3 weeks and when I went to to take it out I noticed my temp gauge was up after being on plane, back to idle and all good, cleaned intake ports on drive and no difference, anyways I think I found my problem, about 3000 rpm the water starts to pulsate coming out of the transom to the thermostat housing, i put a new water pocket cover on and sea pump impeller but no change, however I did not change the bottom base but seen nothing wrong with it, i have a video here of what it is doing, this to me makes sense of why it's creeping up while on plane but now I am lost as where to go, i also scoped out power steering cooler and no restriction in there, I ran a wire thru transom tube going thru back of boat, anybody have any suggestions
 

midnightrider1818

Petty Officer 2nd Class
Joined
Aug 17, 2009
Messages
189
Also I do want to make sure I'm looking at this right, I should have more water flow with higher rpms, it should not break up like that right
 
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