u/Emotional-Pin1649

I brought my 2016 Kia niro hybrid in to a shop because the coolant was leaking and I heard a water rushing noise. They said it was due to the cap not fitting, causing the threads on the expansion tank to wear down and allow coolant to leak out.

A couple people said their quote to repair was high so I called around and found a place to do it for about £100 less. Entire expansion tank and cap replaced, direct from Kia.

However, a week later and the problem has returned. Coolant is leaking and the water is back.

Am I in the right to go back to the first place and ask them to diagnose again for free? I think it’s the heat exchange which is a known problem for these cars but when I asked if they checked for that he was so dismissive.