[GlennGeng]

I changed the risers and manafolds, checked flow of pumps.Boat stays cool at low rpm and idle. When take it over 2k rpm, motor quickly over heats. Looking for answers. Tks Glenn

[ColoradoDiablo]

Drive Impeller , engine water pump , thermostat stuck , blockage in system. I'd check those first.

Larry

[DFZ272]

How did the temp look before you changed the risers and manifolds and why did you change them? Is this engine fuel injected or carb? Are you doing this test in the water or on the trailer with muffs while hooked to a water hose? Does the temp go up only under load or also while revving the engine while out of gear? Are all hoses routed properly? What type of exhaust do u have, are they above the water line where u can actually see water coming out of them? Check these things first and let us know what you find? There are some other things that can cause overheating like fuel air mixture, ignition timing, etc but make sure all water is flowing properly first. I know these are more questions than answers, but I hope it gives u a starting point.
Happy Boating
Dan