[KevinW]

Thanks for the suggestion, but I am always paranoid about putting anything onto the threads of fixings going into blind threaded holes for fear of building up pneumatic pressure. I spent a fair bit of time screwing in the bolts and unscrewing them and cleaning the threads to try and get them to go in smoothly - its all done now. Tomorrow is the moment of truth when I'll have some time to top up the coolant and see if it stays inside the engine!