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Mercruiser 30 closed cooling system

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"I have a 1986 18' Sea Ray

"I have a 1986 18' Sea Ray Seville fresh water boat with a Mercruiser 3.0L engine and an Alpha 1 outdrive. I am planning to put it into Salt water.
After reading all the problems salt water does to the engine, I thought that if I hooked up the inlet hose from the outdrive to the manifold/riser in order to cool the exhaust, I could then get hold of a car parts and a radiator and that might keep the engine cool. Does this make sense?"
 
"NO just flush the motor with

"NO just flush the motor with fresh water when you pull it out, if you flush it and wash everything down each time you pull it from the salt water it will be fine."
 
No. A car radiator depends on

No. A car radiator depends on air flowing over the coils to cool the water/anti-freeze inside.
That's why there is a fan behind it for when the
car isn't moving. insufficien air flow in a boat
unless you mount it outside the engine compartment. The engine block and the exhaust/intake manifold are all cooled by sea water - they are not separated. Mercury and some
aftermarket mfgs make systems for that engine.
Requires a sea water cooled "heat exchanger" and
some plumbing parts. On an engine that old you
would probably be OK just flushing with fresh water after each use in the salt.
 
"This boat is a rare find. The

"This boat is a rare find. The boat and engine might be old but the engine has not been run in ten years, (Stored in heated garage) so I'm trying to get another 10+ years out of it. As my wife worked on boats for CrisCraft a few years, we were going to replace all the interior but it is real good shape and will be replacing the rugs only and painting some interior and the hull. There is minor wood replacement to do in the bow.
The other day I removed the exhaust/intake manifold and presurized the block to 15 PSI for 4 hours to check for leaks. Didn't find any. Today, I'll be presurizing the exhaust/intake (manifold/riser?) to check for water leaks. The engine is out of the boat and it turns over nicely. I know that I could hook up some system to be able to flush it with fresh water, but want to make it as easy on myself and just wash the salt off of the hull after boating. Feel that a car Radiator with electric fans would keep the engine cool weither at an idle or at 3-4000 RPM."
 
"Stick w/the heat exchanger sy

"Stick w/the heat exchanger system! If your idea of a radiator and fan worked, don't you think the boat mfgrs. would have done it already? A radiator and fan are much more cheaper than a heat exchanger system. The big drawback of a radiator in a boat is the necessity of volumes of cooler air passing thru it, then exhausting the increased volume of heated air.
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"
 
"A marine engine generates a l

"A marine engine generates a lot more heat than a car engine due to the additional energy required to push the boat through the water. And it operates at a much higher RPM at any speed above idle. All you need to flush the motor with fresh water is a "flushing attachment" that goes over the water intakes in the drive. Like a pair
of earmuffs, hook up a garden hose, turn on the water and run the engine for a few minutes.
If you do try the radiator project we would be very interested in the results with photos."
 
"yeah I want to see where you

"yeah I want to see where you think you can mount it and still get enough air to flow over it
"
 
"Re: "Feel that a car Radi

"Re: "Feel that a car Radiator with electric fans would keep the engine cool weither at an idle or at 3-4000 RPM."

Maybe at idle, but never at 3-4000 rpm under load. Car radiators work in cars because the car is moving along at highway speeds and has ram air cooling it. The electric fans on present day car radiators in cars only operate at idle or at low car speeds. They are thermostatically controlled and only come on when needed. They are NOT the primary air movers past the radiator!"
 
"I still want to see where you

"I still want to see where your going to put it even if you get it to work. I know they use car radiators on air boat but I think the fan they use is a little bigger than the ones they use on a car...
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just think it will look funny with a radiator hanging out on a boat. I hope you aren't planning to put it under the engine cover where there is really NO air flow.."
 
like I said before just flush

like I said before just flush it. I have had boats around salt water almost all of my life and have gotten way more then 10 years out of a boat that is properly maintained. Just get yourself a good set of muffs and hook it up to the garden hose. Something else about your idea is that even if you put a closed system on motor you will still need to flush it everytime due to the outdrive will still be pumping salt water.
 
I agree with bill I have a 3.7

I agree with bill I have a 3.7L merc and I usee it in Salt more than fresh water and everytime I use it in salt I flush it and have had no problems yet
 
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