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View Full Version : Freshwater cooling: whole versus half systems



Ghost
08-22-2010, 04:07 PM
I'm curious why Merc and Volvo seem to offer only half systems (antifreeze in the block but raw water in the manifolds and risers). Whereas some other manufacturers (Crusader for example) extend the closed antifreeze system to the manifolds.

Good info on the real pros and cons of each? Obviously a whole system seems preferable for corrosion. Cons? And anyone know why Merc and Volvo both go for half systems?

gcarter
08-22-2010, 06:30 PM
I think part of the answer is to ask how expensive and vulnerable are your exhaust manifolds???????
If you run in salt a lot and have aluminum manifolds, then maybe a full system is preferable.
Stainless Marine's manifold and riser desigh really lends itself to full systems because of the joint design.
The Minx had Stainless Marine manifolds and had a full system.
OTOH, many manifolds like the Stainless and Gil, are coated and aren't likely to corrode.
Anyway, on the TR I'm running a half system w/Gil manifolds because I wanted a good remote system and that's what was available. In both cases though, the risers are SST and won't corrode.
Maybe w/unprotected, ordinary stock type manifolds a full system is in order.

DonziJon
08-22-2010, 08:13 PM
My '86 Minx. I replaced both risers/elbows (Merc cast Iron) at about 13 years old because..as it turns out, one was pissing water into the cylinders on the PORT side.

Everything is fine until last season (24 years old). More pissing. I replaced BOTH the Riser And the Manifold (PORT Side) because I figured the manifold was probably about due. Lets do both. :yes: What a Real PITA that was. Broken bolts......... So now it's all done.

NOW.. After the fact..I take a GOOD look at the old riser which seemed to be fine on first inspection off the old manifold...prior to replacing ALL. The F-in riser had a pinhole. The original old manifold was NOT the problem.

This boat is raw water cooled...and flushed after every use.

There is no magic bullet....except maybe all fancy SS. Somehow I think that people who do the SS Bling Thing exhaust manifolds and headers..don't keep the boat long enough to find out..:bonk:

Never Mind.......DJ

Morgan's Cloud
08-22-2010, 09:18 PM
And let's not forget that a full closed system is going to need a much larger heat exchanger. many engine rooms just don't have the extra space.
(like mine )

Your risers are always going to be a raw dump anyway regardless of full or half fwc , and when you replace them what's a few more bucks for the manifolds ?

And, no , I don't have money to burn .... haha

BigGrizzly
08-23-2010, 10:07 AM
Let me answer the question that was asked. 1) size- the full system needs a significantly larger cooler, ie bigger and a little more complicated hose routing. however the riser are still an issue. 2) cost is more do to the extra, almost double. Since the risers still have an issue it hardly seems worth it. So the use staless steel exhaust so only frezzing is an issue and draining them is easy.

Ghost
08-23-2010, 08:31 PM
So the use staless steel exhaust so only frezzing is an issue and draining them is easy.

Thanks Grizz--I'm curious whose you recommend?

gcarter
08-23-2010, 08:39 PM
Thanks Grizz--I'm curious whose you recommend?

I know, 'cause I bought one myself.
But I'll let him tell you.

gcarter
08-23-2010, 08:57 PM
Oh, what the heck!

http://www.perfprotech.com/store/catalog/High-Performance-Fresh-Water-Cooling-Systems,3203.aspx

Ghost
08-23-2010, 09:49 PM
Oh, what the heck!

http://www.perfprotech.com/store/catalog/High-Performance-Fresh-Water-Cooling-Systems,3203.aspx

LOL, thanks! Was also wondering whose manifolds were recommended. Appreciate all the help.

gcarter
08-23-2010, 09:57 PM
LOL, thanks! Was also wondering whose manifolds were recommended. Appreciate all the help.

I think it's hard to beat Stainless Marine.