Quote:
Originally Posted by nickd
Steve W- I'm not sure I understand what you mean by: the head with the crack on the boss can be repaired, but the other one needs replaced? The other photo shows cracks in the ceramic liner. According to Porsche TSB it isn't anything to worry about until a 1 square cm chunk of the liner is gone. Which is pretty substantial. These ceramic liner cracks don't look nearly as bad as photos that I've seen in other threads.
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Ceramic liner failure is not uncommon on high-mileage engines now as they are all getting old. I have seen pieces of this liner become trapped between the seat & valve when it closes, bending the valve. For that reason, I don't run them when the liner is damaged like that.