We found a heat exchanger here 298633 Westerbeke, Universal, Medalist, Heat Exchanger
. Our engine runs at about 165 under load. I check and replace both the zincs in the heat exchanger and one in the bottom of the coolant tank about every 3 months. We have completely rewired our Oday, so I am confident that it is wired correctly but the marina we are in seems to have a lot of stray voltage and we go through zincs ( both engine and shaft zincs ) about every 6 months. So i change them every 3 months just to be safe. Look at my post about universal engine and call Tractor Smart for your parts, it will save lots of $$$ and they are very helpful. We changed out the thermostat and replaced freshwater cooling side with 50-50 antifreeeze and engine runs at 165 max.