Suzuki DF70 Heating Alarm >3000rpm

[Zijls006]

Hello, I have a heating problem.
My DF70 has just had a service and the impeller has been replaced and also the thermostat has been replaced. If I take the boat and I stay below 3000 rpm the engine runs well. the water jet is good. no problem.
If I want to go faster and go above 3000 rpm then the water jet decreases in power. there is almost nothing coming out of the tube. If I keep going, I'll get a TEMP alarm. If I take the throttle back and go below 2500 rpm again then after 5 seconds the waterpower from the engine increases again and the beam is powerful again.
I am not boating in salt water. Can somebody help me?

[Murray]

Is this a new problem since servicing or is this the reason you had the thermostat and water pump replaced?

[Zijls006]

Hello Murray. No, it was already a problem for the service. I was just testing today. I noticed the heat on the top of the block was very hot.

second test what I did today is connect a water hose directly to the side of the engine. Now the engine stayed nice and even on temperature.

The water jet was also powerful.

I don't think the water supply from the tail is sufficient.