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Discussion Starter · #1 ·
In my time here I have seen quite a few folks reporting coolant levels rising in the coolant overflow tank. I noticed this problem on my car since I have been driving it more this spring. After each drive the coolant level in the overflow tank would rise about 5mm or so hot and never settle back down to the original level. After a few drives the coolant level continues rising until its well above the MAX line. The coolant level in the radiator by then was below the filler neck. I had replaced the cap already last year with a new OEM cap and that is working as it should. I started checking the tube that runs from the radiator to the overflow tank for leaks. All of the connections were tight...except for this one marked by the arrow:

Rectangle Font Parallel Automotive exterior Auto part

The pickup tube was a loose fit to the cap fitting and allowing air in. I had not noticed the loose fit until recently. This rubber tube has swollen over the years and the system will allow coolant to expand into the tank but not allow the system to suck the coolant back in. I replaced this tube with one that fits tight and since I have done that the coolant level rises in the tank hot and then is drawn back into the radiator when the system cools off. The resting level in the overflow tank always stays the same now.

Simple fix that I hope helps someone with this problem. (Will not help a BHG situation unfortunately)
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