Recently I noticed that the Y -shaped pipe near the expansion bottle was cracket and leaking.
Then the coolant started to boil in the expansion tank after driving (temp gauge still at 90).
The Fan kick in as usualy. Car performance is normal.

So, could be the leaking Y-pipe the cause of the boiling in the ex. bottle?
Can be low coolant level the cause of boiling or maybe something else?

Thank you all for answers!!!!