Cold Exhaust Water

[Bob Rutland]

After about an 1 1/2 hour motor, something just didn't seem right with my Yanmar 2gmf. It was running hotter than usual and seemed to be smoking like it was under more strane(I dismissed this because we were towing a dingy).My first thought was that the impeller had gone and we were not pumping water. To check the water output I placed my had over the exhaused pipe. There was plenty of water comming out but it was stone cold ! Could this be caused by the thermostat stuck shut? Thanks, Bob S/V Lady Di II

 

[Gordon Torresen]

Hot engine - cold water

You have your own answer. If the thermostat is stuck, most of the internal water would not get to the heat exchanger where the heat is transferred to the sea water.  There could possibly be other blockage. We recently went after a bad thermostat only to find a gasket from the cap of an antifreeze bottle wedged into it.