Thermostat or hoses?
As you may already know, the 5411 has a somewhat unusual setup in that, until the engine reaches operating temperature, the thermostat directs the output back to the cool water intake so as to pre-heat the incoming water. Therefore, the 5411 has minimal output to the exhaust compared to other boats, even when at full operating temperature. With regard to your problem, I can only think of two things that would cause this to happen: 1. Thermostat stuck or upside down. If you were to remove the thermostat, the engine would act like you describe with high water flow to the exhaust and taking forever to heat up. Are you sure that you re-installed the thermostat properly? Assuming that the thermostat is operating OK (did you test it in a pan of water on the stove?), I can't think of anything else that would cause this to happen. I'm not sure but an upside down thermostat might cause this to happen (I'm not sure that it would fit upside down but it might). 2. The only other thing I can think of is that you somehow mixed up the the output hoses and are sending the water that should be recirculating out to the exhaust.
