Hi, I just replaced the exhaust elbow due to a small leak on my 2gm, raw water cooled. It was original I think on an 82 hull. The elbow and exhaust port on the head were pretty carboned up. I also pulled the thermostat to check flow and discovered it was corroded inop. I also noticed quite a bit of debris in the thermostat housing. So I pulled the housing, cleaned it, pulled the zinc anodes, pulled the thermostat and descaled the cooling system from the input pipe (from the water pump) to the discharge side of the thermostat housing. I plugged the bypass flow to make sure it all went through the cylinder head. While descaling, I pulled the overheat sensor, checked it for operation and verified that the overheat heat sensor worked. By the way, the new sensors are 60 or 65 degree limits. The one I have is white topped listed at 65 degree. So my point is check for flow through the cylinder head. Water in the exhaust might just be bypass flow. Dan, #409
