I brought the car back to them. Turns out it's not the head, it's the crank itself. So they're putting in another engine. (no fee, under warranty)
What are the laws in Quebec, Canada concerning car repairs?
(i'm under warranty on the previous engine (3 months), now will I have another 3 months, or will it be under the same warranty (i'm more sure about that one

Nevertheless, I'll test it when I get it back.