Second attempt trying to get some advice on this one. Would appreciate
any inputs on this problem / solution....

I had an overtemp alarm sound as a result of a damaged seawater
impeller pump on my closed freshwater cooling system. I replaced it and
restarted. I was surprise that the alarm went off again but only when
the RPM were increased. The temp gage was went to normal (1/4) and
stayed there. I rechecked everything I could think of - engine
oil/pressure, outdrive lube, temp and all appeared to be ok. The alarm
will not sound until the engine gets up to temp and I then increase the
RPM to ~1800. After it starts sounding, it will remain sounding until
the engine goes cold and I restart.

My questions a
1) Besides the three items listed above (oil, temp and drive lube) is
there any other thing that will cause the alarm to sound?
2) If I mistakenly mixed the sewater hoses (inlet ond outlet) would
this cause the alarm to sound and would the temp still show "normal"?
3) After I replaced the impeller, the first time the alarm re-sounded
was when I was attempting to adjust the trim, any relation?

Any ideas, inputs or suggestions would be greatly appreciated,