I am putting serious consideration into converting to a closed loop cooling system that uses a heat exchanger instead of pumping raw water thjrough my engines. No need to winterize my engines, and would suspect that coolant would be nicer to my engine internals... Any thoughts on the matter or recommendations would be appreciated.

You would still need to winterize to a certain extent. You need to run AF through anywhere that water runs through. I just don't see a need for it in this area.

Was going to do the same until
I heard the A F could loosen scale
up inside the motor and clog the
exchanger up. Decided not to do it

I have. Used the kit from monitor marine. It works great! 540 alum heads. The idle is so much better with more heat in the engine.
Steve

Nice site. www.monitorpro.com

I converted mine to closed cooling but I am in salt water. Yes AF is slightly acidic and released scale and rust, but since you are in fresh water you probably don't have much. Another benefit is that I could run a higher temp (160deg) thermostat instead of the 143 and the engine will run more efficiently. Maybe in fresh water you can run a 160 with raw water though. Also, the potential for shock cooling (say after raw water pickup clog is cleared) is eliminated as the exchanger acts as a buffer.

The decision for salt water use is easy, for fresh water it's a toss up IMO.

I run 160* stats in my fresh water cooled engines.

All Mercruiser black EFI/MPI engines run 160* tstats also.

I have been running a 400 sbc in my boat for years, I added closed cooling because of hot spots in my rear cylinders because of the cooling patterns with siamezed block and I run salt water also. I found that i can run a 15lb pressure cap and 160 degree thermostat, which took care of my circulation issues and also improved my idle with a hostile cam also intake manifold corrosion issues. I do recomend the change upon rebuild wich eliminates the issue of loosening up of scale left over from raw water cooling.

We design and build closed water cooling systems and would be willing to help with a complete system or simply advice. You can call us at 866-726-COOL. We're an advertiser as well on OSO. But the bottom line is that if you are going to spend a ton rebuilding your engines, it just doesn't make sense not to install the FWC system. All the flexibility the guys talk about above...it's all possible. Gather the information about your engines and call Jim or myself. We'd be happy to help!


Mr. Cool
www.mrcool.us