merc. 3.0 thermostat?

Hi,
This might sound like a dumb question, but while changing the head gasket on
my merc 3.0, I noticed that the thermostat was missing. My question is: why
does a marine engine even have a thermostat? I can understand that in a car
you want the coolant to heat to a certain extent to provide heat to the
interior, but on a boat engine where you have an unlimited supply of cool
water (the river) why would you want the thermostat to prevent cold water
from circulating in an area of the engine untill it reaches it's set
temperature and opens?
Thanks.

Without going into a lot of detail, most engines are designed to be operated
at a certain temperature. Certain tolerances within the engine are designed
to be too tight until the engine reaches operating temp.When the operating
temp is reached, parts expand based on their composition. When these parts
expand, the tolerances also expand in a controlled manner.

Operating significantly below this temperature for extended periods of time
will cause rapid wear, poor performance, and poor economy.

For best performance and reliability, your engine needs a thermostat to
generate enough heat to maintain an optimal temperature.

If you want more detail than this, let me know.

Todd
"B. Alexander" <brock.alexander.DeleteThis@cae.com> wrote in message
news:cck33r$r52$1@dns3.cae.ca...
 > Hi,
 > This might sound like a dumb question, but while changing the head gasket
on
 > my merc 3.0, I noticed that the thermostat was missing. My question is:
why
 > does a marine engine even have a thermostat? I can understand that in a
car
 > you want the coolant to heat to a certain extent to provide heat to the
 > interior, but on a boat engine where you have an unlimited supply of cool
 > water (the river) why would you want the thermostat to prevent cold water
 > from circulating in an area of the engine untill it reaches it's set
 > temperature and opens?
 > Thanks.
 >
 ><!-- ~MESSAGE_AFTER~ -->