Quote: We have an MD2030B. If I run at 3000 rpm for more than 10 minutes the overheat alarm sounds! Probably because the boat is over propped. Doesn't bother me. The boat doesn't go any faster at that engine speed. Only difference is the transom step is awash!
We have an MD2030B as well, and we can run it flat out for as long as wish without it overheating. There must be something wrong with your cooling system (Primary or secondary).
In practice we run it at about 2500 for most of the time, but I don't worry about having it on max if needed - except that it drinks diesel and I'm tight with the diesel bill!
-------------------- “When you discover that you are riding a dead horse,
the best strategy is to dismount.”