Has anyone ever thought of a 'closed loop cooling system'..

....for outboard motors?

Watching gator hunters on TV tonight, I thought to myself "how the hell do they not burn those engines up in all that mud, and hydrilla, etc? You just know those water pumps are ingesting all that crap, and they have to keep shutting down and clearing it, the same way I have to do when I get into mud and sand out here."

And then it hit me. Why not design an outboard with a closed loop cooling system?

Have an electric water pump that runs when the ignition circuit of the engine is running, this would supply coolant to the cylinder head, and then back to the reservoir.

Then have a reservoir (not sure how big it would have to be) to hold the coolant.

And then a heat exchanger plate, or radiator. The heat exchanger could be mounted on the transom, flush with the bottom of the hull, so that water passing across the surface would help cool it down. Or, a radiator, mounted somewhere at the stern, that would be cooled by airflow.

Of course, the cooling system of the cylinder head would have to be re-designed, from a total loss system, to a closed-loop system, meaning, none of the coolant is lost through exhaust or other passages, 100% of it is returned to the reservoir.

But think how great this would be for people who operate in the swamps, or in sand and mud!!


Anyhow, this was one of those ideas that just popped into my head. I was curious if anyone had ever tried anything like this. If so, did it work as expected?

wouldnt that be the same as a mud motor or surface drive motor lol.. good idea though

T-MAN said:

wouldnt that be the same as a mud motor or surface drive motor lol.. good idea though

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Yeah, those go-devils are air-cooled engines, so, it would be the same kind of concept, but it would still be a conventional OBM lower unit, instead of surface drive.

Good idea......hmmm how bout a hovercraft......the military has some pretty interesting closed systems, however you would have to pay $10,000 for the bolts that put it together, and the need to know. :?

This is strange !! I just logged on and I was thinking the same thing this morning. It would be awesome.

Heh....might be practical in some applications....overall I would say it inst though.

RiverBottomOutdoors said:

Heh....might be practical in some applications....overall I would say it inst though.

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I agree, if you wanted to go with a radiator you'd have to mount a fan to cool it, and a pump to circulate the water. Thats going add more electrical requirements. And by the time you give up space to mount a radiator, hoses, pumps, you've given up a good deal of space. Then look what happens when you want to move the motor to another boat. Do you move all the associated cooling with the motor. That takes away the portability. If you decide to upgrade to a larger motor you'd need to increase the cooling capacity for the larger motor. Lots of things to take in to consideration and would only be practical for very specific applications.

Ha! Someone did it!

https://www.youtube.com/watch?v=nZSxKJZZTHc

I saw that video, looks like the closed loop system was working perfectly for that particular application!

So, obviously, it CAN be done, and has been done. Now the question is, how hard is it to make this modification?

I'm still thinking a heat exchanger plate mounted to the transom would act as efficiently as a radiator, in fact, this is how the closed loop PWC's from Sea Doo circulate the coolant.

As far as all the added things that a closed loop system requires....I'm not too worried about having to unbolt and swap engines, etc.....once I put an engine on a boat, that's where it stays, until it dies, or I get rid of the boat, whichever comes first!

bigwave said:

Good idea......hmmm how bout a hovercraft......the military has some pretty interesting closed systems, however you would have to pay $10,000 for the bolts that put it together, and the need to know. :?

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Hovercraft is cool, but I still like my idea of the flat-bottom boat with the snowmobile track, for propulsion across water, and across sandbars. :mrgreen:

Sometimes I think maybe I SHOULD have gone to college, maybe I'd be working for a think tank somewhere, making a helluva lot more than what I make.

Hovercraft is cool, but I still like my idea of the flat-bottom boat with the snowmobile track, for propulsion across water, and across sandbars. :mrgreen:

Now were talking. :LOL2:

bigwave said:

Hovercraft is cool, but I still like my idea of the flat-bottom boat with the snowmobile track, for propulsion across water, and across sandbars. :mrgreen:

Now were talking. :LOL2:

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**** right. Unfortunately, I live on the coast of South Carolina....we don't have any surplus snowmobiles sitting around here for me to buy one and start experimenting.

I'm hoping someone who lives in an area where surplus snowmobiles can be found, will try such a project and let us know how it works out.