Has anyone converted to closed cooling and routed it up through their CMI Headers so that they had a "Full" closed cooling system.

I spoke with CMI the other day and he did mention that he had seen someone who did that and had some strange leaking/pitting as a result of that being the last "stop" in the closed cooling leg and the temperature being higher than a traditional raw water system.

Any thoughts on doing this or should I just convert the Block to closed cooling and leave the exhaust as raw water cooled?

You still need raw water to run to the cooler for the closed system no matter what and Id imagine to cool the headers too you`d need one hell of a bigger cooler and tons of flow.

242ls tried on his cafe with Gil exhaust with no luck that I know of. From what I've read keeping the headers as cool as possible helps there life. I can sorta see that since most headers I've seen that failed were on engines that run at 160-180*, yet big power boats with 2 stage water pumps and running 120* seem to last much longer. Could be total coincidence or the big power boats just don't get any hours on them lol

Corrosion rate is correlated to temperature.

That's my big concern - that after cycling through the oil cooler, PS cooler then through the block that by the time it gets to the end of the line (the headers) that it's going to be too hot.....

What If I just ran it with a crossover and no thermostat? I don't have stats now - was going to switch to them over the winter because I never run the boat long enough to get any heat in it so I wanted to add stats to get the temps up some but could do without if it got the coolant temps down low enough to keep the headers cool