please clarify terminology

[rebars1]

OK, time for a newbie question...Would someone please clarify what the different cooling system terms mean. I see "sea water" pump term used with "raw" water systems and "fresh water" systems. If I'm always on a lake in fresh water, is the "sea water" reference the same? I think I understand that both "open" and "closed" cooling systems need water from whatever you're floating in to circulate through. Is that water "raw", "sea", or "fresh"?

 

[TwoBallScrewBall]

Re: please clarify terminology

"Sea water" pump means it's the pump that pulls in the water that you're boating in. <br /><br />Closed cooling means that this "sea water" is passed through a heat exchanger, basically the boat equivalent of a car radiator. It's a brass tube that has two separate chambers. One chamber is sea water, brought in from the sea water pump and out through the exhaust. The other chamber circulates anitfreeze, just like in a car. The antifreez circulates through the block and is cooled by the sea water in the heat exchanger.<br /><br />Raw water system just does not have a heat exchanger or antifreeze, the sea water is pumped directly into the engine block for cooling, and then out the exhaust. <br /><br />"Raw" and "Sea" water are typically the same thing, "Fresh" water is typically antifreeze-mix.

 

[metwrench]

Re: please clarify terminology

EXCELLENT Description Capt Steve !

 

[rebars1]

Re: please clarify terminology

Thank you. So, with and open system, the sea/raw enters the boat (in hoses) through the pump in the lower unit then is pumped again by the pump on the engine through the engine then out. On a closed system, the sea/raw water pump in the lower unit circulates outside water through the heat exchanger and out, while pump on the engine circulates the antifreeze mix through the engine.<br />By jove, I think I've got it. Thanks again!

 

[Dunaruna]

Re: please clarify terminology

Bingo, except you don't mention what type of outdrive or motor you have. Some outdrives don't have pumps in the lower unit and some motors don't have circulation pumps. Confused yet <br /><br />Aldo

 

[rebars1]

Re: please clarify terminology

Dunruna:<br /><br />I have a 1971 Trisonic Mercruiser 888, Ford V8 302, 188hp, with a raw water cooling system, Pre- Alpha outdrive.

 

[Dunaruna]

Re: please clarify terminology

Originally posted by rebars1:<br />[QBI have a 1971 Trisonic Mercruiser 888, Ford V8 302, 188hp, with a raw water cooling system, Pre- Alpha outdrive. [/QB]

Then you've got it in one.<br /><br />Aldo