full fresh water cooling system for a 3.0 Mercruiser

[Bogdat]

Has anybody heard of a full fresh water cooling system for a 3.0 Mercruiser? I'm told that Merc has never made one for the 3.0L
but make a half system.

It looks like its possible to tweak the half system into a full system by placing a blanking plate on the
exhaust manifold blocking off the water escape and allowing only the fumes to escape out the riser.

This would allow the exhaust manifold to be filled with coolant, no sea water.

The coolant in the exhaust manifold will need to be piped back to the circulating system to create flow resulting in cooling.

I have an alpha one leg that I forgot to mention.

So has anyone tried this? Is it possible? Am I missing the obvious?

bt

 

[HT32BSX115]

Re: full fresh water cooling system for a 3.0 Mercruiser

...

 

[Bogdat]

Re: full fresh water cooling system for a 3.0 Mercruiser

Thanks for the reply Rick

What you describe is what I plan to do, but wasn't sure if I was missing the obvious. As you say the system may not be large enough, so I was planing to install a
lower temp thermostat and run some infra-red temps on the system putt around first and see how it copes and slowly open it up.

I have contacted Merc but they failed to come up with an answer. I will chase your suggested contact and see what they say.

Thanks again

 

[Bondo]

Re: full fresh water cooling system for a 3.0 Mercruiser

Has anybody heard of a full fresh water cooling system for a 3.0 Mercruiser? I'm told that Merc has never made one for the 3.0L
but make a half system.

It looks like its possible to tweak the half system into a full system by placing a blanking plate on the
exhaust manifold blocking off the water escape and allowing only the fumes to escape out the riser.

This would allow the exhaust manifold to be filled with coolant, no sea water.

The coolant in the exhaust manifold will need to be piped back to the circulating system to create flow resulting in cooling.

I have an alpha one leg that I forgot to mention.

So has anyone tried this? Is it possible? Am I missing the obvious?

bt

Ayuh,... Welcome Aboard,....

A few years ago,...
FreebeTony did a closed cooling conversion on his I6 mercruiser...
I remember it well,....
Search the archives, or pop off a pm to Tony,...
I'm sure he'd help...
I believe he started with a V8 sized exchanger, 'n We figured out his plumbin' from there....
I sent 'im a hose nipple end cap for his exhaust manifold to route the manifold water back to the exchanger...

I don't remember what he did for a T-stat housing though....

 

[achris]

Re: full fresh water cooling system for a 3.0 Mercruiser

.... As you say the system may not be large enough, so I was planing to install a
lower temp thermostat and run some infra-red temps on the system putt around first and see how it copes and slowly open it up....

Using a lower temperature thermostat will not change anything, the engine will still be producing the same amount of heat, just less efficiently. If you have access to another heat exchanger try cascading them (just remember to run the water in opposite directions to each other. Seawater in one direction, engine water opposite). As for the thermostat, you need to put a hotter one in, not colder. The reason raw water cooled engines have cooler 'stats is because at the higher temperatures seawater disassociates into hydrochloric acid and attacks softer metals. Change the stat to a 180 degree... The engine will run more efficiently and could actually produce less heat in the process...

 

[mikeboat1]

Re: full fresh water cooling system for a 3.0 Mercruiser



Ayuh,... Welcome Aboard,....

A few years ago,...
FreebeTony did a closed cooling conversion on his I6 mercruiser...
I remember it well,....
Search the archives, or pop off a pm to Tony,...
I'm sure he'd help...
I believe he started with a V8 sized exchanger, 'n We figured out his plumbin' from there....
I sent 'im a hose nipple end cap for his exhaust manifold to route the manifold water back to the exchanger...

I don't remember what he did for a T-stat housing though....

Hey bondo hi,

I know it's along time ago, but hope you can help me out.
I want to convert to full fresh water system.
I now have a 1/2 system with a 6 cyl heatexchanger.
I know that I would need a riser block off plate but can't find one or part number.
Can you guide me in how I can convert to a full system.

Thanks,
Mike.