On Oct 8, 11:55 pm, Wayne.B wrote:
On Mon, 08 Oct 2007 22:05:17 -0500, wrote:
Looking back now, I'd gladly pay the extra $1000 if the benefits are as
described. New manifolds and risers run about $6-700 also.

I sure someone will correct me if I'm wrong but, IIRC, the fresh water
cools only the engine. Salt water is still used to cool the fresh
water (in the heat exchanger). It is pumped in from the sea with the
standard water pump in the lower unit and returns to the sea by way of
the exhaust manifold(s), just like standard cooling. So if you're
thinking you'd be saving the manifolds from seawater's rust and
corrosion, you'd be wrong (if I'm right in my recollection).

It depends. Some FWC systems cool the manifolds with coolant, others
with raw water. The risers/elbows still see raw water regardless.
Obviously if the manifolds are still being cooled with raw water their
life expectancy will not be increased by FWC, only the block and
heads.

That's why they don't really save that much. The risers are the part
that goes first with raw water cooling and no closed system includes
those. The only thing you save with a closed system is the exhaust
manifolds. You can cool a marinized auto engine with salt water
forever without any major effects. Salt water is not going to damage
a block. There are engines out their in fishing boats that have been
in them 20 years using salt water to cool the block. And closed
systems are not without their own problems with the exchangers and all
the additional plumbing.