I have a Mercruiser 140 hp straight 4 cylinder engine in a boat
which I want to keep in the lake and have available all year.
Usually it doesn't stay cold for long periods at a time here, but
this year it has been freezing or below for about a week or more.
I've kept the motor from freezing by using a handy little item
called a Thermo Cube:

http://tinyurl.com/yeg3jgl

and some lights, but wanted to winterize the motor for while
until things warm back up to normal. There is one drain cock on
the right side of the motor. I emptied that, and then dumped in
antifreeze at the top of the motor where the thermostat goes. I
left the cock open until antifreeze started coming out of it,
then closed it and continued filling with pure antifreeze until
it came to the top of the thermostat opening. That should mix
with whatever little water is left and keep the motor safe from
freezing at least down to zero degrees, right?

Also, I'm wondering if there is any reason to have a thermostat
on a boat that takes water in from the lake. Some people have
told me they are of no use, but others apparently put them in
since there is one in this boat. It is old and looks like it
probably doesn't work any more, and the spring has broken loose
from it. Would it be just as well to get rid of it and not use a
thermostat at all?

wrote:
I have a Mercruiser 140 hp straight 4 cylinder engine in a boat
which I want to keep in the lake and have available all year.
Usually it doesn't stay cold for long periods at a time here, but
this year it has been freezing or below for about a week or more.
I've kept the motor from freezing by using a handy little item
called a Thermo Cube:

http://tinyurl.com/yeg3jgl

and some lights, but wanted to winterize the motor for while
until things warm back up to normal. There is one drain cock on
the right side of the motor. I emptied that, and then dumped in
antifreeze at the top of the motor where the thermostat goes. I
left the cock open until antifreeze started coming out of it,
then closed it and continued filling with pure antifreeze until
it came to the top of the thermostat opening. That should mix
with whatever little water is left and keep the motor safe from
freezing at least down to zero degrees, right?

Also, I'm wondering if there is any reason to have a thermostat
on a boat that takes water in from the lake. Some people have
told me they are of no use, but others apparently put them in
since there is one in this boat. It is old and looks like it
probably doesn't work any more, and the spring has broken loose
from it. Would it be just as well to get rid of it and not use a
thermostat at all?

The deep vee hull I ran with a Mercruiser 110 had several engine block
drain cocks.
The manual ought to spell this out.
Removing the thermostat risks running the engine too cold.
Your method of backfilling with (animal-safe) antifreeze keeps the water
as slush even with very low temperatures, unless there are crannies
where no antifreeze reaches.

Brian W

wrote in message
...
I have a Mercruiser 140 hp straight 4 cylinder engine in a boat
which I want to keep in the lake and have available all year.
Usually it doesn't stay cold for long periods at a time here, but
this year it has been freezing or below for about a week or more.
I've kept the motor from freezing by using a handy little item
called a Thermo Cube:

http://tinyurl.com/yeg3jgl

and some lights, but wanted to winterize the motor for while
until things warm back up to normal. There is one drain cock on
the right side of the motor. I emptied that, and then dumped in
antifreeze at the top of the motor where the thermostat goes. I
left the cock open until antifreeze started coming out of it,
then closed it and continued filling with pure antifreeze until
it came to the top of the thermostat opening. That should mix
with whatever little water is left and keep the motor safe from
freezing at least down to zero degrees, right?

Also, I'm wondering if there is any reason to have a thermostat
on a boat that takes water in from the lake. Some people have
told me they are of no use, but others apparently put them in
since there is one in this boat. It is old and looks like it
probably doesn't work any more, and the spring has broken loose
from it. Would it be just as well to get rid of it and not use a
thermostat at all?

Your method of winterizing might be OK, but a 40w bulb in there, as John
says, is a good idea.

Regarding the thermostat, John is also correct there. Engines are designed
to operate most effeciently in a particular temperature range. When you
first start the engine, the thermostat is closed restricting the coolant
flow, until a particular temp is reached. Then it opens, and the coolant
flows and goes to work...attempting to maintain that range in temp.

In the case of a boat, cooled with very cold raw water, the thermostat may
(and does) actually close while running to get the temp back up. Your engine
may seem to run fine without it, but you'll get better fuel economy and
performance with it.

--Mike

On Wed, 6 Jan 2010 18:13:12 -0800, "mgg" wrote:

In the case of a boat, cooled with very cold raw water, the thermostat may
(and does) actually close while running to get the temp back up. Your engine
may seem to run fine without it, but you'll get better fuel economy and
performance with it.

And longer engine life also. Running cold increases friction and
wear.

"Wayne.B" wrote in message
...
On Wed, 6 Jan 2010 18:13:12 -0800, "mgg" wrote:

In the case of a boat, cooled with very cold raw water, the thermostat may
(and does) actually close while running to get the temp back up. Your
engine
may seem to run fine without it, but you'll get better fuel economy and
performance with it.

And longer engine life also. Running cold increases friction and
wear.


Absolutely correct!

--Mike