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What's the key to identifying cooling system type?

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I'm facing my first winterizing of my 2001 Response (had it done for me all these years), and reading over all the info, there's clearly a difference between the open, semi-closed, and closed cooling systems. My Indmar manual is, of course, generic and non-specific. What's the big clue as to what kind I have? And, given positive ID on the cooling system, are there any engine-specific instructions?

Thanks...from a new member, but an old Malibu owner.

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Do you know what engine you have?

Also you might was to post some pics of your engine compartment which will give us a clue to the type of cooling system you have.


Well, I've always been a little confused on that. The engine says "Vortec", but it's clearly EFI (no carb, and there are injectors), so I've always thought it was the

Indmar 325HP Monsoon 350ci EFI. BTW, we are original owners, it came this way, no mods have been done.

Is there a place for coolant/anti-freeze?

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@jaddie: one tell tale sign of a closed cooling system will be a water to water heat exchanger, one that has 2 water inlet and 2 water outlet hoses. If only one heat exchanger and it has only one water in and one water out along with 2 transmission lines it will be an open cooling system and you will need to drain all the water out. Make sure you drain both sides of the block, drain the exhaust manifolds and if you have a heater, make sure you drain that also. It is a pretty good idea to refill with RV antifreeze to ensure you did not leave any water in the system and have some antifreeze protection. If you have a shower, drain that also. Can the previous winterizer shed some light on your system?

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  • 2 weeks later...

Can the previous winterizer shed some light on your system?

We paid for winterizing and storage, I doubt I'd be welcomed to walk in and ask, since we aren't working with that outfit anymore. The issues were cost and damage/sloppiness. Always had to clean up after them, and often had to fix something they broke.

Thanks all for the advise. Next time I'm by the boat I'll post an engine shot, just to be sure.

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