My car (Peugeot 406 1.8 16V) has an old-fashioned radiator without a separate coolant overflow tank. It is an integrated unit. The manual only shows the newer models equipped with overflow tanks. There are six lines. I marked the minimum (lowest) and maximum (highest) lines in the picture.

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Line A = Min

Line B = Max

I believe the max line means the coolant must be there when the engine is hot and running (has reached its operating temperature). In other words, coolant level must not be there when the engine is stone cold. I also believe that somewhere between A & B (maybe between 3rd & 4th lines) is the correct level when the engine is cold.

But I might be wrong!

1 Answer 1


The coolant level will fluctuate between when it is hot and cold (as you were surmising). While the Peugeot 406 owner's manual does not state exactly where it should be at any given time (hot or cold), typically for most vehicles which have the type of overflow yours does requires the level to be between the lines whether hot or cold. IOW: it shouldn't be over the top line when hot and not below the bottom line when cold. As long as it stays anywhere in between during any given time, you should be right in the ballpark of where it needs to be.

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