Hello all I'm the proud new owner of the Catalina 36 "Mistral". I've replaced all the seawater hoses for the engine cooling system today. Before I tackle the anti-freeze system I thought I would check the hot water. I ran the engine (Universal M25XP) for about 40 minutes at the dock at about 1950 rpm. the engine temperature stayed right about 155. The hot water never really got very hot. Could it be the thermostat?
Thanks all!
Mic in Seattle
I have a C36 with the Universal M25 engine. My water gets hot running the engine at idle; I will certainly have hot water after 40 minutes of idling ('though I usually don't idle at the mooring, I am usually charging batteries while I'm making hot water, so I run it at about 2,000 RPM, in order to get the right speed for the alternator.
Has the water ever gotten hot for you, or is this a new thing since you replaced the seawater hoses?
155º seems low to me. If I recall correctly I have a 170º thermostat in mine. When all is well, it stays right at 170º. Maybe someone put a lower temp thermostat in because the engine was overheating. Do you have the larger heat exchanger, 3", or the original 2"? You should get the 3" heat exchanger if you don't have it.
There should also be a bypass valve that allows you to control how much flow is directed through the domestic water heater. If the valve is closed all the way, all of the engine coolant must pass through the water heater. Under full load, this constriction may result in overheating. But for fastest water heating at the dock or mooring, close this valve all the way. If you anticipate motoring soon, or don't want to keep fooling with it, keep it 1/2 open and watch for overheating at full load.
