Originally Posted by Capt.Alex
Could be a small amount of scale in the heat exchanger
. It may be time for a descaling bath.
That's a good point. The engine
does go above the temperature that the thermostat is all the way open when the engine
is operated at full RPM
. This indicates to me that the heat exchanger
is not getting rid of the heat in the coolant
like it should. I would pull the heat exchanger and take it to a radiator shop to have the exchanger hot tanked. This should remove scale both inside the tubes and on the outside of the tubes inside the exchanger where you cannot see the scale.