heating at 3000rpm

[mamoka]

hy
I just buy a hunter 33.5 1992 with a yanmar 3gm30f and the old owner but bigger pipe before and after the water filter because his motor was heating after 3 min at 3000rpm and over,That does,nt change anything .I would like to know what can I do to resolve my problem.
thank,s
jean-pierre

 

[Cayennita]

Have you cleaned the heat exchanger, check the impeller, cleaned the thruhull, cleaned the strainer? One important item is to see the flow of water out of the back. I found that my exhaust hose was collapsing at higher RPM's. Because of age, it had become soft and was restricting the flow and creating back pressure. I replaced it and no more overheating. Another problem could be a combination of larger alternator and engine driven refrigeration plus the two water pumps plus motoring. Asking a lot out of the engine.