closed cooling

barnyard

Seaman Apprentice
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Jul 29, 2016
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just rebuilt engine SBC 5.7. Want to install closed cooling. For full system dd you need sea water pump? Outdrive is Alpha one 2nd gen. vendor said pump in outdrive is sufficient
 

Bondo

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just rebuilt engine SBC 5.7. Want to install closed cooling. For full system dd you need sea water pump? Outdrive is Alpha one 2nd gen. vendor said pump in outdrive is sufficient
Ayuh,..... It'll have to be a Huge H/E for a full system,.....
 

cyclops222

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Mar 21, 2024
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Cooling system could cost as much as the complete engine rebuild. Check if the top of the exhaust manifolds will clear engine hatch cover when closed. 3" is not enough space to prevent heat discoloring the cover. All the extra hoses may not clear room walls or items on the walls.
Reason for doing the conversion ?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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if the heat exchanger is properly designed, it can work with the lower flow of the Alpha raw water pump.

going full system, the heat exchanger will be at least 5" in diameter with a core at least 21" long for a low output 5.7 liter

a full system has twice the BTU capacity as a half system

are you going 4-pass, or 5-1/2 pass?

full kit, or a build your own system?
 

ROY WILLIAMS

Chief Petty Officer
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Aug 8, 2022
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just rebuilt engine SBC 5.7. Want to install closed cooling. For full system dd you need sea water pump? Outdrive is Alpha one 2nd gen. vendor said pump in outdrive is sufficient
various engine 5.7L cooling antifreeze 50% and distilled water 50%.
outdrive pump water Maintenace.
 

Lou C

Supreme Mariner
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Nov 10, 2002
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13,178
Cooling system could cost as much as the complete engine rebuild. Check if the top of the exhaust manifolds will clear engine hatch cover when closed. 3" is not enough space to prevent heat discoloring the cover. All the extra hoses may not clear room walls or items on the walls.
Reason for doing the conversion ?
If you are in freshwater it might not seem as important but here in the salt pond, there is no way I'd put in a reman or new engine without it. In fact in my mind that is the one of the few advantages of an inboard vs an outboard, here a closed cooled inboard could actually last longer than an outboard.
 

kenny nunez

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Jun 20, 2017
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3,352
I beg to differ about the drive pump being enough to cool a F/W conversion.
Years ago I tried it, the V8 engine would overheat above 3k rpm. I know the drive pump will keep an inline engine with F/W cooling and maybe a V6 but I learned the hard way about V8s.
I never got to try it with a Alpha 2 system so possibly that drive could do it.
Mercruiser says in their service manual to integrate the drive supply with the belt druven pump. That makes it ”bullet proof”. Just my humble opinion.
 
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