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Old 27th March 2024, 14:23   #10
SD1too
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Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model.

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Quote:
Originally Posted by bl52krz View Post
The ‘wush’ You heard was air going in the tank, not coming out. As the water cools, the level drops. When you undo the top, air rushes in to replace the vacuum that has been caused.
If that's the case then the valve in the expansion tank cap, designed to prevent the creation of a vacuum, isn't working.

Simon
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