Closed cooling option?

[avdoc]

On my '77 Cobalt, would I benefit any by changing to a closed cooling system? This is a fresh water boat. Would I just add a radiator, fan, different water pump, t-stat, then run the headers out the back? It seems something would have to be changed in the out drive too maybe. I think it's an alpha 1. If I could do this, my only accomplishment may be a little more power, but will make it more "car like" other than the spark arrestor on air breather, starter, alternator, dist. etc. Am I missing something here, and would this work be of ANY real benefit? I am obviously looking for something to accomplish on this thing before spring. I am strange that way I guess.

 

[Don S]

Re: Closed cooling option?

Boats don't have radiators and fans, they have heat exchangers that are cooled from the water on the outside of the boat.
DO NOT fix or change anything on your boat to automotive until you understand the systems and how a marine engine and drive works.

 

[avdoc]

Re: Closed cooling option?

Boats don't have radiators and fans, they have heat exchangers that are cooled from the water on the outside of the boat.
DO NOT fix or change anything on your boat to automotive until you understand the systems and how a marine engine and drive works.

So it would be like when I use a heat exchanger to help cool the intercooler for the turbo on one of my cars. It only uses fresh water to cool the closed cooling system. Brilliant idea, I'll probably just leave it like it is, just wanted to learn how this stuff works. I just ask my questions different than you would....

 

[DJ]

Re: Closed cooling option?

Understood. Maybe I did not phrase the question appropriately. Do you still use the "heat exchangers that are cooled from the outside water" if you switch to a closed cooling system?

The short answer is yes. Closed cooling systems use a heat exchanger which is essentially a water to water radiator. Water is pumped through the heat exchanger by the engine cooling pump (either in the outdrive or engine driven) and circulated from there. Some systems cool the manifolds also.

The primary advantages of closed systems is twofold.

1. You can run the engine hotter which is more efficient.

2. You protect the engine from tainted and/or salt water.

I wouldn't bother on a boat of that age. I remember reading here (probably from Don S, Bondo or rodbolt) that MerCruiser does not recommend installing a kit on anything over two years old, as I recall.

 

[magster65]

Re: Closed cooling option?

Understood. Maybe I did not phrase the question appropriately. Do you still use the "heat exchangers that are cooled from the outside water" if you switch to a closed cooling system?

Yes, the heat exchanger uses the water you're floating in to cool it.
If you only run in fresh water, don't bother... there's nothing to gain really other than you could install a hydronic/buss heater in the system. The closed cooling system is more of a benefit to those of us that boat in the salt.

 

[avdoc]

Re: Closed cooling option?

Thanks guys. That makes sense. I am learning, so bear with me. I come from a long history of motorsports, and not watersports.

 

[starsnstripers]

Re: Closed cooling option?

My boats 38yrs old and i'm installing a heat exchanger closed system for sure. Salt water use here.

 

[achris]

Re: Closed cooling option?

My boats 38yrs old and i'm installing a heat exchanger closed system for sure. Salt water use here.

Sorry sns, complete waste of money... Those old 250 blocks don't have a problem. You're putting a new manifold on so no problems there either.... Why complicate things?

Chris...........

 

[starsnstripers]

Re: Closed cooling option?

Well, I have the right therm. housing and I found a heat exchanger and spare manifold w/riser for 100.00 in good shape. The manifold i have on the 250 isn't new but in ok shape. Going to use the 2nd manifold for the 292. I guess i like the idea of keeping the salt out and the antifreeze in. I'm hoping to run the engine coolant through the manifold to prolong manifold longevity too.

 

[DJ]

Re: Closed cooling option?

Well, I have the right therm. housing and I found a heat exchanger and spare manifold w/riser for 100.00 in good shape. The manifold i have on the 250 isn't new but in ok shape. Going to use the 2nd manifold for the 292. I guess i like the idea of keeping the salt out and the antifreeze in. I'm hoping to run the engine coolant through the manifold to prolong manifold longevity too.

The only way to save the manifold is to have a complete closed system. Most systems do not cool the manifold(s). Cooling the manifold(s) takes a much larger exchanger.

I don't know what you have but it may not be a system capable of handling the manifold heat also.

 

[starsnstripers]

Re: Closed cooling option?

L6 1969-70 165hp 250ci 4" heat exchanger

 

[achris]

Re: Closed cooling option?

L6 1969-70 165hp 250ci 4" heat exchanger

Not big enough to handle the manifold heat. Block and head only....

 

[oops!]

Re: Closed cooling option?

closed in fresh is a compleate waste of time.
you only run the bote 10 deg hotter. whats the benifit?

i ripped mine out.

 

[starsnstripers]

Re: Closed cooling option?

Equipment longevity! Why do they have the system? 10 deg. a little economy edge, outdrive only winterizing, if a head gasket fails etc. Salt dont mix good with metal.

 

[starsnstripers]

Re: Closed cooling option?

Why did you take yours out? did it fail? do you run in salt/fresh water?

 

[Robj]

Re: Closed cooling option?

Sorry Oops, but freshwater cooling is the way to go. Having said that, I do not think that I would changing over a raw water cooled engine to a freshwater cooled one, unless I had a really great boat that was going to live in saltwater. Don't think it is worth it. You can run significantly hotter with freshwater cooling which improves performance and reduces engine wear. My engine runs at about 190 to 200 degrees F, have a 180 t-stat. Raw water cooled engines run a 140 deg t-stat. But then again you will be chasing bikinis in the Okanagan where it is freshwater, so it is not as big a deal. The only raw water cooling you will need is for yourself!! lol

Avdoc, I would probably just leave yours boat as it is.

Have a great day,

Rob.

 

[starsnstripers]

Re: Closed cooling option?

Yeah! what he said^^^ My boats worth a 50.00 heat exchanger. And it's gonna live in the Atlantic OCEAN.

 

[starsnstripers]

Re: Closed cooling option?

Oh, And with the gas prices i want all the efficiency i can get.

 

[achris]

Re: Closed cooling option?

Oh, And with the gas prices i want all the efficiency i can get.

Put that 292 in and ya gunna need it.

 

[starsnstripers]

Re: Closed cooling option?

HA! HA! Chris Well there ya go, With a little warmer eng. operation will help. I wont need such a big tanker!!!