I am buying a used boat from Stony Point, NY. It has a Mercruiser V8
5.0 with 190 HP with 300 hours on it.
I live in Greenland. An island in the arctic region east of Canada
where the seawater temperature is around 36-37 F degrees. And that´s
where there might be a problem. I am told that the motor is "use" to be
cooled of with warmer water temps around the more southern part of the
world. And when I get the boat and the motor is cooled down with
seawater that is 36-37 F degrees then it migth not run smooth anymore
or develop somekinda problem. Is this story a myth or is there
something to it? And if the story is right how can i prevent any
problem with the motor. I cannot install fresh water cooling system as
it is too late for this motor because it has already 300 hours of
seawater cooling I am told.
Any help or suggestions will be much appreciated.

Thanx
jens erik
Nuuk
Greenland

wrote in message
ups.com...
I am buying a used boat from Stony Point, NY. It has a Mercruiser V8
5.0 with 190 HP with 300 hours on it.
I live in Greenland. An island in the arctic region east of Canada
where the seawater temperature is around 36-37 F degrees. And that´s
where there might be a problem. I am told that the motor is "use" to be
cooled of with warmer water temps around the more southern part of the
world. And when I get the boat and the motor is cooled down with
seawater that is 36-37 F degrees then it migth not run smooth anymore
or develop somekinda problem. Is this story a myth or is there
something to it? And if the story is right how can i prevent any
problem with the motor. I cannot install fresh water cooling system as
it is too late for this motor because it has already 300 hours of
seawater cooling I am told.
Any help or suggestions will be much appreciated.

Sal****er cooling is 'uncontrolled' water circulation drawn from under the
boat- with very little control of the engine operating temperature. If you
are concerned about 'stabilizing' the engine temperature, the only way to do
it is by freshwater cooling. This will allow the engine to run at operating
temperature (controlled by the thermostat) and at least run more efficient.
And it is NOT too late to do this.

The raw ater cooled engine has a thermostat, same as an automobile
engine, that will control the temperature of the water running through
the motor. The thermostat is low compared to say a closed system engine
.... around 140 F or so (?) ... and that's because if the water is too
warm, it'll dump the salt out ... and that would be bad for the engine.


OT: I myself would never buy a used I/O sight unseen ... there are just
too many things that could be wrong ... bad risers, and on, and on, and
on.

Just to amplify the following advice a bit, engines run most efficiently
when HOT! The only reason your auto engine doesn't run a lot hotter is that
it's too hard to keep the pressure reasonable when you go much above 212 F.

The other potential problem is "shock cooling." Idle a bit and then turn
the engine off. Heat will percolate out from the exhaust and from the
combustion chambers. When it's started again, the cold water will cause
different parts of the engine to shrink at different rates and you can get
piston scuffing at least and possibly other dire actions.

That said, there isn't that much difference between the Caribbean's 85
degree water and your 37 degrees. The effects are calculated on the
"absolute" temperature scale, so it's 545 to 497 (10%) on the Rankine scale.

Roger

http://home.insightbb.com/~derbyrm

"theMooseisLoose" wrote in message
news:8kuKf.34509$6f2.19385@trnddc02...
wrote in message
ups.com...
I am buying a used boat from Stony Point, NY. It has a Mercruiser V8
5.0 with 190 HP with 300 hours on it.
I live in Greenland. An island in the arctic region east of Canada
where the seawater temperature is around 36-37 F degrees. And that´s
where there might be a problem. I am told that the motor is "use" to be
cooled of with warmer water temps around the more southern part of the
world. And when I get the boat and the motor is cooled down with
seawater that is 36-37 F degrees then it migth not run smooth anymore
or develop somekinda problem. Is this story a myth or is there
something to it? And if the story is right how can i prevent any
problem with the motor. I cannot install fresh water cooling system as
it is too late for this motor because it has already 300 hours of
seawater cooling I am told.
Any help or suggestions will be much appreciated.

Sal****er cooling is 'uncontrolled' water circulation drawn from under the
boat- with very little control of the engine operating temperature. If you
are concerned about 'stabilizing' the engine temperature, the only way to
do
it is by freshwater cooling. This will allow the engine to run at
operating
temperature (controlled by the thermostat) and at least run more
efficient.
And it is NOT too late to do this.

The raw water cooled Mercruiser does have (or should have) a thermostat in
its thermostat housing located on the top and front of the motor. The
thermostat will be a 140 deg as the other poster said and you engine will
warm up and run fine. A "fresh water" system is helpful for keeping the
cooling passages in the block and heads from rusting thru or clogging with
chunks of rust but is not necessary to keep you engine at the proper temp. I
think one of the worst things about running such a set up in salt water is
not running the boat often. When these systems sit up for expended periods
big globs of rust can form and clog up something, like the exhaust elbow.

--
Ron White
Boat building web address is
www.concentric.net/~knotreel

Re the difference - it's significant.
This is a heat transfer / cooling issue, not one where you can apply the
ideal gas laws and use Rankine or absolute temperatures.
If the engine block is at say 250F, the rate of cooling for 37 F coolant vs
85 F is (250 - 37) / ( 250 - 85).
More importantly, if temperature difference required to remove the developed
heat is say 100F, it will run at 185F in the Caribbean and 137 in the colder
water ...
You can't just restrict the flow or the temperature becomes uneven. So you
need a circulating system - might as well consider a fresh water one ..
David

"derbyrm" wrote in message
news:xBuKf.788735$_o.605338@attbi_s71...
Just to amplify the following advice a bit, engines run most efficiently
when HOT! The only reason your auto engine doesn't run a lot hotter is
that it's too hard to keep the pressure reasonable when you go much above
212 F.

The other potential problem is "shock cooling." Idle a bit and then turn
the engine off. Heat will percolate out from the exhaust and from the
combustion chambers. When it's started again, the cold water will cause
different parts of the engine to shrink at different rates and you can get
piston scuffing at least and possibly other dire actions.

That said, there isn't that much difference between the Caribbean's 85
degree water and your 37 degrees. The effects are calculated on the
"absolute" temperature scale, so it's 545 to 497 (10%) on the Rankine
scale.

Roger

http://home.insightbb.com/~derbyrm

"theMooseisLoose" wrote in message
news:8kuKf.34509$6f2.19385@trnddc02...
wrote in message
ups.com...
I am buying a used boat from Stony Point, NY. It has a Mercruiser V8
5.0 with 190 HP with 300 hours on it.
I live in Greenland. An island in the arctic region east of Canada
where the seawater temperature is around 36-37 F degrees. And that´s
where there might be a problem. I am told that the motor is "use" to be
cooled of with warmer water temps around the more southern part of the
world. And when I get the boat and the motor is cooled down with
seawater that is 36-37 F degrees then it migth not run smooth anymore
or develop somekinda problem. Is this story a myth or is there
something to it? And if the story is right how can i prevent any
problem with the motor. I cannot install fresh water cooling system as
it is too late for this motor because it has already 300 hours of
seawater cooling I am told.
Any help or suggestions will be much appreciated.

Sal****er cooling is 'uncontrolled' water circulation drawn from under
the
boat- with very little control of the engine operating temperature. If
you
are concerned about 'stabilizing' the engine temperature, the only way to
do
it is by freshwater cooling. This will allow the engine to run at
operating
temperature (controlled by the thermostat) and at least run more
efficient.
And it is NOT too late to do this.

Good answer. I was wondering about the same issues. Not to throw dirt at
anything because I love the motor, I have heard through the grapevine that
the Mercruisers "like to be dry" ...rust easily. At this point, that's only
a rumor, but the point is that a nice salt-free freshwater system and good
ventilation would be good for the motor (any motor, really.)

Brian D



"David Flew" wrote in message
...
Re the difference - it's significant.
This is a heat transfer / cooling issue, not one where you can apply the
ideal gas laws and use Rankine or absolute temperatures.
If the engine block is at say 250F, the rate of cooling for 37 F coolant
vs 85 F is (250 - 37) / ( 250 - 85).
More importantly, if temperature difference required to remove the
developed heat is say 100F, it will run at 185F in the Caribbean and 137
in the colder water ...
You can't just restrict the flow or the temperature becomes uneven. So
you need a circulating system - might as well consider a fresh water one
..
David

"derbyrm" wrote in message
news:xBuKf.788735$_o.605338@attbi_s71...
Just to amplify the following advice a bit, engines run most efficiently
when HOT! The only reason your auto engine doesn't run a lot hotter is
that it's too hard to keep the pressure reasonable when you go much above
212 F.

The other potential problem is "shock cooling." Idle a bit and then turn
the engine off. Heat will percolate out from the exhaust and from the
combustion chambers. When it's started again, the cold water will cause
different parts of the engine to shrink at different rates and you can
get piston scuffing at least and possibly other dire actions.

That said, there isn't that much difference between the Caribbean's 85
degree water and your 37 degrees. The effects are calculated on the
"absolute" temperature scale, so it's 545 to 497 (10%) on the Rankine
scale.

Roger

http://home.insightbb.com/~derbyrm

"theMooseisLoose" wrote in message
news:8kuKf.34509$6f2.19385@trnddc02...
wrote in message
ups.com...
I am buying a used boat from Stony Point, NY. It has a Mercruiser V8
5.0 with 190 HP with 300 hours on it.
I live in Greenland. An island in the arctic region east of Canada
where the seawater temperature is around 36-37 F degrees. And that´s
where there might be a problem. I am told that the motor is "use" to be
cooled of with warmer water temps around the more southern part of the
world. And when I get the boat and the motor is cooled down with
seawater that is 36-37 F degrees then it migth not run smooth anymore
or develop somekinda problem. Is this story a myth or is there
something to it? And if the story is right how can i prevent any
problem with the motor. I cannot install fresh water cooling system as
it is too late for this motor because it has already 300 hours of
seawater cooling I am told.
Any help or suggestions will be much appreciated.

Sal****er cooling is 'uncontrolled' water circulation drawn from under
the
boat- with very little control of the engine operating temperature. If
you
are concerned about 'stabilizing' the engine temperature, the only way
to do
it is by freshwater cooling. This will allow the engine to run at
operating
temperature (controlled by the thermostat) and at least run more
efficient.
And it is NOT too late to do this.

You're right regarding the cooling capacity. I was addressing the size
changes of the metal parts.

Roger

http://home.insightbb.com/~derbyrm

"David Flew" wrote in message
...
Re the difference - it's significant.
This is a heat transfer / cooling issue, not one where you can apply the
ideal gas laws and use Rankine or absolute temperatures.
If the engine block is at say 250F, the rate of cooling for 37 F coolant
vs 85 F is (250 - 37) / ( 250 - 85).
More importantly, if temperature difference required to remove the
developed heat is say 100F, it will run at 185F in the Caribbean and 137
in the colder water ...
You can't just restrict the flow or the temperature becomes uneven. So
you need a circulating system - might as well consider a fresh water one
..
David

"derbyrm" wrote in message
news:xBuKf.788735$_o.605338@attbi_s71...
Just to amplify the following advice a bit, engines run most efficiently
when HOT! The only reason your auto engine doesn't run a lot hotter is
that it's too hard to keep the pressure reasonable when you go much above
212 F.

The other potential problem is "shock cooling." Idle a bit and then turn
the engine off. Heat will percolate out from the exhaust and from the
combustion chambers. When it's started again, the cold water will cause
different parts of the engine to shrink at different rates and you can
get piston scuffing at least and possibly other dire actions.

That said, there isn't that much difference between the Caribbean's 85
degree water and your 37 degrees. The effects are calculated on the
"absolute" temperature scale, so it's 545 to 497 (10%) on the Rankine
scale.

Roger

http://home.insightbb.com/~derbyrm

"theMooseisLoose" wrote in message
news:8kuKf.34509$6f2.19385@trnddc02...
wrote in message
ups.com...
I am buying a used boat from Stony Point, NY. It has a Mercruiser V8
5.0 with 190 HP with 300 hours on it.
I live in Greenland. An island in the arctic region east of Canada
where the seawater temperature is around 36-37 F degrees. And that´s
where there might be a problem. I am told that the motor is "use" to be
cooled of with warmer water temps around the more southern part of the
world. And when I get the boat and the motor is cooled down with
seawater that is 36-37 F degrees then it migth not run smooth anymore
or develop somekinda problem. Is this story a myth or is there
something to it? And if the story is right how can i prevent any
problem with the motor. I cannot install fresh water cooling system as
it is too late for this motor because it has already 300 hours of
seawater cooling I am told.
Any help or suggestions will be much appreciated.

Sal****er cooling is 'uncontrolled' water circulation drawn from under
the
boat- with very little control of the engine operating temperature. If
you
are concerned about 'stabilizing' the engine temperature, the only way
to do
it is by freshwater cooling. This will allow the engine to run at
operating
temperature (controlled by the thermostat) and at least run more
efficient.
And it is NOT too late to do this.

Your engine as supplied by the factory, has a thermostat, just like an
automotive thermostat. It is located so that the water is warmed by the
exhaust manifold before entering the engine and the thermostat does not let
excessively cold water enter the engine. The water is allowed into the
engine when it is at the proper temp. Thus the engine operates at it's
ideal temp.

You may be anticipating a non existent problem unless someone has removed
the thermostat, in which case, put one back in.

Don Dando

wrote in message
ups.com...
I am buying a used boat from Stony Point, NY. It has a Mercruiser V8
5.0 with 190 HP with 300 hours on it.
I live in Greenland. An island in the arctic region east of Canada
where the seawater temperature is around 36-37 F degrees. And that´s
where there might be a problem. I am told that the motor is "use" to be
cooled of with warmer water temps around the more southern part of the
world. And when I get the boat and the motor is cooled down with
seawater that is 36-37 F degrees then it migth not run smooth anymore
or develop somekinda problem. Is this story a myth or is there
something to it? And if the story is right how can i prevent any
problem with the motor. I cannot install fresh water cooling system as
it is too late for this motor because it has already 300 hours of
seawater cooling I am told.
Any help or suggestions will be much appreciated.

Thanx
jens erik
Nuuk
Greenland

way's why the Mercruiser and all the other I/O systems that use automotive
engines( that I know of) do have a circulating system, same as you car.,and
raw water flow isn't restricted by the thermostat on the inlet. They
actually have been engineered to account for your concerns and ,amazingly
they do work, with or with out "closed loop" exchanger system. The decision
weather to use closed loop fresh water system is more often a practical one,
if the engine is dificult (expensive)to remove or not is a big consideration
(plus freezing concerns). The point being, why spend something like
500-1000 bucks for the exchanger system to protect a cheap car engine? The
cooling system corrosion issues won't make the engine last forever anyway?
That is unless you engine is buried deep under some nice stuff rather than
being under a lift up engine cover as most of these setups are. To an extent
you could think of these ase thowaway engines. They are relatively
un-expensive and have limited useful life. Oh, but their cooling systems do
work!

--
Ron White
my boatbuilding web site is:
www.concentric.net/~knotreel