Took head to bloke who did machining for me he checked it and two things first head is 2 thou out across the length and he told me the liners in 2 and 4 had one edge raised by just over a thou when he took the block in first time and it was fine when pressure tested so armed with that and the fact there was no steam cleaning evidence I am going to rebuild and if it fails then whip when lot out and have new liners preferably when it is warmer and lighter