BoatBanter.com - A question on thermostats

JohnH wrote:
On Mon, 10 Jul 2006 18:11:08 -0400, "Eisboch" wrote:

" JimH" jimhUNDERSCOREosudad@yahooDOTcom wrote in message
...

"Eisboch" wrote in message
...

"JimH" wrote in message
oups.com...

I did notice the temperature ran at 135 when at idle, at 140~145 at
cruise
and at 160~165 at WOT, then back down immediately to a lower
temperature
when at cruise or idle.

I plan to keep the 140 in the rest of the season.

Is that engine raw water cooled or does it have a heat exchanger and
closed loop cooling?

Eisboch

Raw (fresh) water cooled. The good news is that the temp never got above
165. The bad news is that it fluctuated to an extreme. I am concerned
about the way the temperature is bouncing around as I am used to seeing it
rise to a certain temp and stay there.

I will definitely be bringing the boat to a reputable mechanic at the end
of the season to take a close look at the engine, knowing a rebuild or
replacement may be the result. I don't, however, want to throw away the
rest of the season by doing that now if I can limp through this problem
without causing further damage to the engine or causing another overheat
situation.

My memory is bad, but if I recall correctly the raw water cooled 350
Mercruiser clone engine that I had in an old 26' Century 10-11 years ago
normally ran at about 140-145 degrees, even at full throttle. Then one day,
out of the blue, it suddenly started to climb up to the 160 -165 degree
range. Manifolds were shot. I realize you run in fresh water and the
manifolds should last a little longer, but something sounds familiar here.
Sorry to give you more to worry about, but the manifold failure can be
sudden and disastrous for the engine under the right (or wrong)
circumstances.

Maybe someone with more accurate knowledge or memory will elaborate.

Eisboch

When they decide to go, it can be a costly mess.
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John

It looks like you may have been spot on all along John.

Thanks.

Jim