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Discussion Starter #1
Can we convert the 65-68 "open" cooling system to a "closed" system simply by connecting the radiator overflow tube to the bottom of a resivoir so it can give-and-take the coolant as needed? Then add an overflow tube to the resovoir.

As we know, some cars find their own level in the radiator below the cooling fins. This is my situation with my 68. It has no leaks, (been pressure tested, vaccum runs steady) and the system (t-stat, pump, hoses, new 3-row radiator) seems to be working properly. With no apparent head gasket leak. (I am planning a compression test for later this week)

I was hoping to make this change to ease my mind and elimminate the constant topping off of the coolant. I am not looking to simply catch the overflow, but have it available for the system to draw off of as needed.

Thanks
 

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Thats the way mine is setup. ;)
 

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You will need to replace the 'open system' style cap with one for a 'closed system'. The difference is that a closed system cap seals at both the top & bottom of the radiator neck. That forces the expanding fliud to travel to the overflow tank, and return to the radiator as the engine cools, creating a vacumm in the radiator.
 

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Discussion Starter #4
Thanks, is this a good idea? Do you anticipate any down-side to this?
 

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That's pretty much all a closed system is. You do need to make sure you have a radiator cap for a closed system (allows the vacumn to suck the coolant back in). I would recommend one of the stainless tube type cans, they are much nicer looking and hot temperatures don't bother them - you can also get them cheap on Ebay usually, not much more than a cheapo plastic one at a parts store.

There is no downside to this mod (IMO), there are upsides though. The biggest is that it eliminates air from your system. Rust forms when metal oxidizes, so less air means the water passages have less rust over time. Less air also means fewer hotspots.

John Harvey
 

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EJKanter sells the stainless steel ones for about as good a price as anyone through his company, Kanter Performance, and I like supporting other VMFers when I can.
Thanks a lot. You just made me spend $60. :p
 

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Ran a 2 liter Coke bottle wrapped with duct tape for over 6 months . Just took the tube from the radiator neck and stuck it in the top without a cap .The tube needs to reach near the bottom of the bottle .
 
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