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Old 11-17-2015, 01:01 PM   #29
R_p_ryan
Senior Member
 
City: San Francisco
Vessel Name: Shellbourne
Vessel Model: 1978 Mainship 34 Perkins T6.354
Join Date: Dec 2014
Posts: 171
Quote:
Originally Posted by sunchaser View Post
RPR

Why not just bite the bullet and buy a new unit suited for the engine? The current setup has lasted nearly 40 years if I read your posts correctly. Sure sounds like it worked very well.

As discussed, you can make it better by plumbing the manifold for coolant. And you can install a fresh water flush for the cooler. These are sensible upgrades and would be appreciated by the next owner.

But the other stuff you are contemplating are out of the norm and a step backwards IMHO.
My concern is adding too much heat to the raw water system by just adding the manifold into the freshwater circuit. If there was a larger sized OEM heat exchanger designed for the extra heat added from the manifold then it would be a simple and appropriate solution. I haven't seen this, so I'm considering alternative ways to increase the cooling capacity, seeing a cheap titanium heat exchanger sounded interesting. (to refugio it sounds so stupid it's worthy of ridicule, but I am actually a reasonably accomplished engineer and I've faced similar criticism for both - ideas that have worked and ideas that have not. So I've learned to notice yet ignore such ridicule).

I have heard of two situations where the manifold was just added, in one case it was perfectly fine, in the other there were issues which led the owner to repower. I think if the cooling circuit is in pristine shape then there is enough cooling capacity, however if there are any issues - from a worn water pump cam to fouling in the air charge cooler, my guess is the system overheats.

As Cappy points notes it about the BTU of the existing system, the addition of the manifold and the capacity of any added exchanger. I don't know those numbers. I haven't seen a "generic" marine-purpose heat exchanger with BTU ratings.

Thanks,
Robert
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