Pros and Cons of Enclosed cooling system vs. Raw Water system

[mt_bulldawg]

Hi,

We're looking at a smaller Ciera with 5.7 Mercruiser with an enclosed cooling system. Boat is in great condition, motor is well taken care of with about 750 hours. And it's dirt cheap.

The boat is used inland - freshwater only. I would also use it on lakes only. I've had I/O's with "raw" water cooling and have always winterized them myself. What exactly is involved with winterizing an enclosed system - I really would like to do some early spring and late fall (into Nov.) fishing on Flathead here, but don't want to have to go thru the steps necessary to winterize like I've had to do with raw water system - each and every time I take it out when there's a risk of freezing temperatures.

Is there an advantage of enclosed systems in this regard? Any other thoughts on one cooling system vs. the other? Thanks in advance.

 

[G-Daddy]

Re: Pros and Cons of Enclosed cooling system vs. Raw Water system

Well, for the closed loop you need to make sure the coolant will protect your block just like you would an automotive cooling system. My boat is a straight inboard - Mercruiser 350 MAG MPI - with manifolds and exhaust elbows raw water cooled. It has a fitting where I shut the seacock and plug in a section of hose. Then I put three gallons of RV antifreeze in a bucket, drop the end of the hose in the bucket and run the engine until I see pink antifreeze coming out the exhausts. Then I shut her down and she's ready for her long winter's nap.

 

[Kaplooi]

Re: Pros and Cons of Enclosed cooling system vs. Raw Water system

Even with closed cooling your not completely off the hook when winterizing. Your exhaust manifolds, risers and intake tubing will be full of raw water. At a minimum you will still have to empty those out just as you would a raw water cooled engine. In theory you shouldn't have to touch anything that's inside the closed loop (i.e. block, intake manifold, thermostat housing, etc). You probably have to empty your heat exchanger too if it doesn't self drain.

Just as an aside concerning single point drains if you're considering fitting one to 'simplify' matters I've never once emptied out a manifold or block individually and not had to dig some sand or rust bits out with a wire to get it to start draining. Unless you know exactly how much water you should be getting out of all your flooded components and you can measure what you get out, don't trust any single point drain as they can easily get blocked up.

 

[moetr]

Re: Pros and Cons of Enclosed cooling system vs. Raw Water system

1999 Sea Pro 235WA I bought this off Ebay and what a project. Anyway, fish lake Superior and trolling it was not running smooth and one riser was always hotter than the other. I added a San Juan closed cooling, full system, and now it runs all day at 160, excellent. My system self drains. I pull the drain plugs off the risers and pull the zinc anode from bottom of heat exchanger tank but only a few drops of water comes out. Nothing in raw water feed either. I don't think I need to do any winterizing at all which is great for late fall fishing. You would need to make sure everything drains on your boat. I didn't do anything else last year and we hit -30 below. I love the system but it is more crap in the way for repair, etc. Runs better, better on engine with constant temp, etc. I am in cold lake so big plus and no issues overheating with stock outdrive pump. My engine was salt water so I don't expect it to last very long but who knows. I did replace exhaust. If engine ever goes I plan on replacing with crate GM long block truck engine with no mods, $2000 on ebay to door. With antifreeze you don't need brass plugs or special head gaskets, I don't think.

I believe cooling system pressure will go up vs raw water cooled.