Hope they check the obvious!
Jan: Hope that they have check all the obvious problems (new impeller, new belts, mixing elbow, strainer etc). Assuming that all of these have been checked I would think that it is something weird like a water hose that is collapsing or some type of blockage in the exhaust hose when it heats up. I do not know if you have a heat exchanger or raw water cooled model. If you have fresh water cooled model, you need to start at the water intake and make sure that you are sucking raw water into the strainer. Then just keep going. Be sure water is comming into the raw water pump and then out of the pump. If you have an exchanger, then you should just clean it out as a Preventative Maintenance measure. I would also be sure that the exhaust hose is OK. They can get bubbles inside the hose and of course these will expand when the hose gets hot. This hose is expensive so I would be sure before you replace it. Also usually a SOB to get out of the boat.
