If you cooling system uses raw water then normal temp should be around
140-150. It sounds like maybe you're thermostat is sticking. Or something
did not get assembled correctly when when you put the new one in maybe? New
water pump was the pump in the lower unit? Or the recirculating pump on the
front of the engine?

"Jlhornsby" wrote in message
...
I have an '89 Chaparral 198XL w/ 5.0L Mercruiser 305 and Alpha I outdrive.
Ususlly performs great, but after the boat sat for approximately 6 weeks,
I did
some work rewiring the nav lights. This rewiring may be unimportant, but
you
never know. Put the boat back in the water, the temp guage didn't work
and the
temp buzzer went off after a few minutes of run-time. So far, I've
replaced
the Thermostat the temp guage. Now, the temp guage climbs as the motor
warms
up, but never breaks 200. Then the temp guage falls back about 50 degrees
and
the temp buzzer goes off. About 2-3 years ago, had a new water pump
installed.
Probably less than 30 hours on it since then. Not sure where else to go
with
this. Thanks for any suggestions?