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Subject 1 Quart Coolant Overflow Tank okay?
Posted by nissubaru on July 12, 2018 at 9:18 AM
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Message I gave Ash's writeup on the cooling system a read which if I'm understanding it correctly, it sounds like 1 quart might be just fine.

My reasoning? Based on these statements:

"The most widely known principle is that for every pound of pressure in a closed system the boiling point is increased three degrees. For example a 16-lbs. cap increases your boil-over point to 260 degrees (16x3=48). In most cases your motor will be junk after running above 230 for any length of time. But this pressure will suppress boiling while running and boil-over during heat swell that occurs when the engine is shut off. "

"Overflow Tank:
Sometimes referred to as an expansion tank or air separator. Keeping the system full reduces aeration and allows it build pressure faster. As temperature increases the water expands and pressure builds. If the system is completely full the expansion pressure will exceed the cap pressure and over-flow into the recovery tank. Since our pressure cap is properly located at the highest point of the system, the air will be pushed out first. When the system cools and contracts a vacuum is created. Your radiator cap is equipped with a valve that opens under this negative pressure and will draw coolant back into the system through the tube that extends to the bottom of the recovery tank. If the recovery tank is kept half full (with the engine cold) every heat cycle will automatically purge more air out of the system. Potentially, the opposite is true without a recovery system. With every heat cycle water will be pushed out, leaving more air space this air space reduces the system pressure and boiling point."

Based on this info what I think I'm hearing is that coolant isn't pushed out of the system into the overflow tank but rather it's just air. The coolant that sits in the overflow tank even when cold is simply there in case coolant is missing? Which in a properly filled and bled system should mean there is no coolant missing? Upon cooling down the vacuum created will suck coolant back into the radiator if needed.

Am I understanding this correctly? I plan to use this Moroso unit which only has 1 quart capacity.

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