water cooled vs closed system

[simple]

Why do some mercruisers come with closed cooling systems (have antifreeze) and others are just plain water cooled? Can you people explain the differences?

 

[ziggy]

Re: water cooled vs closed system

the closed system does have anti freeze, just like your car does. i'm thinking the reason for haveing a closed sys. is that it would be much less corrosive on the inside of the engine. the raw water cooling system circulates whatever lake your in, or more to the point ocean (salt water, which promotes corrosion a lot). the closed system would not have this corrosion takeing place in the engine with the closed system. however i think the closed system also has an open portion to it. this may go to sea-cocks, sea strainers, exhaust manifolds and heat exchangers and oil coolers. this part of a closed system is much like just plain raw water cooling system. jim

 

[tommays]

Re: water cooled vs closed system

it really comes down to money and space<br /> <br />a closed (FWC) system is allways better it allows the motor to run at a higher temp about 30 deg more than a raw system this lets the motor run more effiecently and it will stay at much more even running temp<br /><br />the hard part is that a heat exchanger cost more money and its very hard on modern boats to find a place for the exchanger that does not make it even harder to work on the motor<br /><br />IMHP the best systems will cool the motor and manifolds and only send raw water through the ellbows<br /><br />i believe if the general public were more aware of the long term advantages you would see very few RWC motors <br /><br /><br />RAW cooled gets the job done for the least amount of money and does work well and with so many boat builders trying to get you money any way to get a price edge is fair game<br /><br />tommays

 

[WillyBWright]

Re: water cooled vs closed system

Closed cooling is an absolute must in saltwater for longevity. In fresh water, it's not at all unusual for a raw water motor to last decades. In salwater, you'd be lucky to get one decade out of it with raw water cooling (depending on maintenance of course).

 

[waterone1@aol.com]

Re: water cooled vs closed system

I agree with the other posts. It's more expensive, but worth every penny if you are in salt water. I wouldn't think about buying a used salt water boat that was raw water cooling, but wouldn't mind at all if it was closed cooled, especially if it was inboards.

 

[MrBill]

Re: water cooled vs closed system

Besides the issues raised already by others, closed cooling makes winterizing very simple for those in cold climates. On my 1989, its as easy as draining the heat exchanger and fogging the engine. After fifteen seasons, virtually no corrosion. I've never heard of a cracked block from freezing with a closed cooling system.

 

[Boatist]

Re: water cooled vs closed system

Very good posts and I agree with them all but you should also be awear of the bad side.<br /><br />If you should have a water leak you will run out of coolent and the engine will over heat. In a sea water system a small leak does not matter as you are always filling the motor with water. Yes you might get a little water in the bildge. Closed system the motor can run out of water just like your car.