How does raw water cooling work?

[lowkee]

A seriously newbie question, I know. I vaguely understand the principal behind the path the water takes through the block and whatnot. What baffles my is the how you have water and fuel sharing a manifold and how it passes the water out.

Is there a site with an animation of a raw water engine on the net somewhere?

I find it a little humorous I just went through a good portion of the Merc 3.0 in my boat without knowing squat about the innards of the cooling system. Granted, I have yet to work up the courage to crack open the stern drive.

 

[Don S]

Re: How does raw water cooling work?

On a 3.0L engine, the intake and exhaust manifolds are all one casting. Basically there are seperate opening in the manifold for exhaust gases, intake from the carb, water for cooling the hot exhaust. They shouldn't ever come in contact with each other. The water passages surround the hot exhaust passages to keep them cool, while the intake really needs to be cool so you don't get vapor lock.
Go up to the adults only sticky and download manual #13 for your engine an #6 for your drive. Look at the flow diagrams and I think you will soon understand.

 

[chiefalen]

Re: How does raw water cooling work?

Ok we will use your 3.0 as a example.

Water is pulled up thru the drive via, a water pump, cooling the drive, into that long hose from the transom to the t-stat.

The water then is diverted to the engine mounted water pump, pumped thru the head via cooling passages, down holes to the block water passages and out passages in the manifold to the riser exterior passages,the exhaust gases are expelled in a jacket of water cause they are in the center of the riser. Than the gases and water are mixed in the exhaust hose and tube down thru the drive.

 

[lowkee]

Re: How does raw water cooling work?

Thanks guys, I'll be sure to check out the flow diagrams in the manuals. I have yet to see an animation of how it works, but if I find one I'll be sure to post it for future newbies like myself.