Engine won't do "flat out"

[alan_fincher]

If you check the thermostat it should be marked not much below 90 deg (raw water ones can be very low temp though), the coolant pipes should be 'very hot to the touch'.

Hi John,

 

Actually if you approach Calcutt to see you a thermostat for a keel cooled BMC 1800, they will suggest either a 74 degree one, or an 82 degrees.

 

When I asked, they wanted to know if the boat had a calorifier. They will generally recommend the 82 degree stat if it doesn't, but suggest only 74 degrres if it does, to avoid the possibilty of people taking skin off with water coming from the hot tap.

 

Of course if the calorifier has a proper mixing valve to limit the temperature of the hot water drawn off, then an 82 degree stat in the engine would be fine. (If you look up the commercial use of the engine in, say, a Sherpa van, then 82 degrees was the stat used in automotive use.)

 

Stating the obvious, but there is obviously no need for the cooling pipe back from the skin tank back to the engine to be 'very hot to the touch' - unless you are thrashing your engine against the flow of a river, it's better if it's pretty cold, as it indicates the cooling tank has a lot of margin still to lose extra heat.

 

With the problem we had with an underspecced ccoling tank, there wasn't a lot of difference in temoerature between the pipe taking hot water to the tank for cooling, and the (allegedly!) cooled water being fed back to the engine - hence the engine cooling water started to go above thermostat opening temperature.

Edited April 30, 2008 by alan_fincher