[C320-list] High Engine Temp Alarm

[Scott Thompson]

Kurt R. Budelmann, M.D. wrote:
> I was running the engine full throttle to come into a protected harbor in advance of a severe thunderstorm when the alarm went off.  The water was 86 degrees and the air temp was 93 degrees.  The engine temp was 200 degrees.  I stopped engine to release suction at water intake and then restarted engine and let it idle and eventually the temperature came down.  Water was coming out of the exhaust port.  At the dock while the storm was raging I made sure the strainer was clear, water was pouring through the filter when I opened the seacock briefly, the impeller checked out and there was enough coolant.  Do I have a thermostat problem or was I running the engine too hard?  Any other ideas?
> __
> Kurt R. Budelmann
> Everwind, Catalina 320 #1035
>   
Two thoughts:

If the prop is over-pitched or fouled with barnacles, etc. then the
engine may not be able to get to max RPMS and pushing the throttle wide
open will only cause it to run badly without achieving max RPMs and
possibly overheat.  Black smoke out the exhaust from incomplete
combustion is a symptom of this.  (I'm pretty sure that my Gori 2-Blade
folder installed two years ago is over-pitched.)  In theory there is no
such thing as running the engine "too hard" for relatively short
periods.  But that's assuming that everything is set up right and
working properly.

It could be that you have a partial blockage of the raw water system.
In this case everything would seem to be fine at idle because the
impeller is turning relatively slowly and the blockage does not
substantially impede water flow.  But if you rev up the engine under
such circumstances the resistance from a partial blockage could prevent
sufficient flow.  Flow should be higher at higher RPMs because the pump
is turning faster.