Hi everyone, I was given a friend's '92 Escort with a 1.9 engine that was leaking coolant into a combustion chamber due to a small channel eroded into the head. The car is in excellent condition otherwise so I had the head milled to clean up the damage, and had a valve grind and jet-clean done.

Now as I put it back together I notice tiny hairline cracks between the valve seats at their closest distance to each other. There weren't any previous problems with the car before the recent leakage, so I wonder if these cracks can be ignored. I'm guessing by the carbon pattern on the cracks that they've been there for a long time.