Overflow bottle

[Andrewh]

Hi, need some advice. I did a coolant change and in the process discovered the plastic overflow has a cracked section and hole in it near lid. Very brittle. So it fills with water as the hole is further up the bottle, way above the level. I have put some tape over hole it until I get a replacement. Is the bottle under pressure. Figure it will be fine? Appreciate second opinion, thankyou