I'm not an expert but yes you should have a thermostat. Theres no reason why you'd ever want to run at only 110.
Do I understand this correctly, that you are circulating sea water and have an open water system/(no radiator)? Like an outboard pisser system?

 

I'm not an expert but yes you should have a thermostat. Theres no reason why you'd ever want to run at only 110.
Do I understand this correctly, that you are circulating sea water and have an open water system/(no radiator)? Like an outboard pisser system?

Yes, rather than having a closed cooling system, where fresh water (non-sea water) is cooled by circulating it through two large exhaust manifolds which are being cooled by sea water, the 'open' cooling system simply circulates raw sea water through the engine. This works very well but to avoid corrosion it's best to flush the system with fresh water often. I'm thinking that with the thermostat the raw cooling water will be allowed to heat up quickly and hopefully stay around 160º. I welcome any and all elaboration on this neophyte theory. Thanks!

 

You are axactly right, currently it is too cold.
160° would be the bare minimum and thats really still too cold, 180-190° would be a better place to be.
Bore wear starts to really climb the wear curve below 180°, and at 160° it is significantly shortening the life of the engine.

 

You are axactly right, currently it is too cold.
160° would be the bare minimum and thats really still too cold, 180-190° would be a better place to be.
Bore wear starts to really climb the wear curve below 180°, and at 160° it is significantly shortening the life of the engine.

Thank you for that! I also have a 180º thermostat and if it's advisable I will install that today. Fortunately the new engine has not been run for any length of time. Thanks again. Larry

I would never ever subject it to salt or brackish water, that said I’m a zero fan of raw water cooling systems even in fresh water. They run the engine much too cold and in the case of salt and brackish water expose the cooling jackets to excessive corrosion and mineral deposition especially where aluminum parts are involved.

110 is way too cold, two things happen with this the first especially in humid environments is the oil doesn’t get hot enough to drive out condensated water that accumulates from the blow by and vent breathing from the atmosphere, these waters entrained in the oil form acids and sludges that etch internal parts especially multilayer metals like bearings and of course anything aluminum and accumulate sticky goo to burnt and hard chard deposits inside the oily parts of the engine. Second is getting to proper operating clearances the lack of this greatly accelerates wear and produces excessive blow by, since blow by is mostly water vapor with a little oil vapor thrown in one can see how this develops a negative feedback loop for contaminating the lube oil.

To an extent these negatives can be reduced with frequent oil and filter changes and cooling system flushes which get to why I don’t play with boats as after having one a long time ago when I lived in San Diego after a couple years it became apparent the the fun didn’t compensate the work and cost involved. So I stick with hotrods, airplanes and motorcycles. Those are enough of a Zen experience for me.

Bogie

Bogie, I guess you won't be buying my boat any time soon. The boat's original 350/300hp SBC engine I replaced was 45 years old and had many hundreds of hours of running time in salt water. It still ran fine, I just wanted more HP to use a bigger prop, and the peace of mind I get from the new long block, and adding newer technology add-ons. It had good compression in all 8.

When the engine was torn down, believe it or not, it was found to be in pretty good condition throughout. The previous owner had the boat for at least 24 years and reported the engine had not been fully rebuilt during his ownership. He obviously took very good care of it. Keep in mind that perhaps 30% of all inboard boats are seawater cooled. The cost of conversion to a closed, heat-exchanger system is too great to consider for most folks. I intend to flush the engine with fresh water after every other usage and treat it to an anti-corrosion product once in awhile.

The points you made are spot on! Yes, raw water cooling is not ideal but taken care of, the engine will last a long time. And besides, it's not easy to fish from a hotrod, airplane or motorcycle.

 

I would never ever subject it to salt or brackish water, that said I’m a zero fan of raw water cooling systems even in fresh water. They run the engine much too cold and in the case of salt and brackish water expose the cooling jackets to excessive corrosion and mineral deposition especially where aluminum parts are involved.

110 is way too cold, two things happen with this the first especially in humid environments is the oil doesn’t get hot enough to drive out condensated water that accumulates from the blow by and vent breathing from the atmosphere, these waters entrained in the oil form acids and sludges that etch internal parts especially multilayer metals like bearings and of course anything aluminum and accumulate sticky goo to burnt and hard chard deposits inside the oily parts of the engine. Second is getting to proper operating clearances the lack of this greatly accelerates wear and produces excessive blow by, since blow by is mostly water vapor with a little oil vapor thrown in one can see how this develops a negative feedback loop for contaminating the lube oil.

To an extent these negatives can be reduced with frequent oil and filter changes and cooling system flushes which get to why I don’t play with boats as after having one a long time ago when I lived in San Diego after a couple years it became apparent the the fun didn’t compensate the work and cost involved. So I stick with hotrods, airplanes and motorcycles. Those are enough of a Zen experience for me.

Bogie

 

About running temperatures, I found this article:

Besides exposure to corrosive materials in the water, raw-water cooled engines suffer from another drawback. They have a thermostat, just like all engines, but it's regulated at 145-150° F. This is done to minimize the possibility that salt in the salt water would separate out and crystallize inside the engine’s cooling passages, with 160°F being the critical turning point for this to occur. This comparatively cool running temperature limit the engine’s ability to reach a maximum level of thermal efficiency, which in turn has a negative impact on fuel economy and to some degree overall engine longevity. The cooler temperatures also cause varnish and gum buildup inside the engine, which ultimately contributed to other problems.

The trick with any engine is to get it running as hot as it can run without causing any damage. That’s when you know it’s running at peak efficiency, assuming proper fuel and exhaust system design.