I've spoken to the mechanic and he hasn't actually removed the head to see the full extent of the damage but he has now agreed that unless something really catastrophic has happened, I shouldn't need a new engine. He's calling me in the next day or two to let me know the damage (both financially and mechanically). Thanks for taking the time to reply. I wanted to upvote your comment but I've lost my slider after delegating 250SP and can now only upvote at 100% until I get another 100SP. Thanks for taking the time to comment.