www.iFourWinns.com

Friend of mine just bought a 1987 Sundowner 195, with 4 cylinder engine and Merc Alpha drive. He'll be joining the forum shortly and posting pics. He is new to powerboats (sailor), and so I helped him in surveying this boat. It is in incredible condition, super clean. One thing I noticed is a water tank on top (to the side) of the engine with a radiator cap. One hose runs from that to a longer cylinder type tank along the bottom of the engine. Is this a closed cooling system? If so, how does it work? Does the water/antifreeze mix in the two tanks circulate through the engine cooling it with fresh water from drive intake cooling the antifreeze? I did not see any type of "radiator" setup, to cool the coolant. I have never owned a closed cooling system boat, so this is new to me...

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

Yup. Sea water cools the antifreeze in a heat exchanger (a tank with coils in it). No air cooling like a car. If it's a normal system it just cools the block not the manifolds so they still rust in salt.

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1981 Columbia 8.7
2015 Yamaha FZR - 87mph - sold
2006 Yamaha GP1300R - sold
2003 Chaparral 215 SSI - sold
2009 Stingray 195CS - sold
2000 Four Winns H180 - sold
1976 O'day Daysailer II - sold
Rick's Four Winns H180 Mods/Upgrade Thread

Thanks, kinda figured thats how it worked. So, that means for winterization (yeah, I know, too early to talk bout that), just drain the exhaust manifold and make sure the coolant mix is adequate? No need to drain the engine?

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

Well you need to drain the raw water side of the heat exchanger and impeller, but the antifreeze stays in the engine. In this case you can use the suck a.f. up the out drive method of winterization instead of draining. Some systems do also include the manifolds. That will make the engine last much longer than open cooling.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Ok, thanks. I'll pass it along to my buddy. Since I will more than likely end up being his go to guy for boat info (until he joins up here), I look forward to learning the closed cooling system.

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X