Replacing cylinderhead

[Ian Williams]

Thank you Ruairidh, I asked because you were at one time very strongly on the Copperslip camp, something I have had past success with on engines with excellent mating faces. And yes two years ago I was using Hylomar spray, it seemed to be effective a lot of the time however I have not hat complete reliability particularly with higher compression ratios. What I am most curious about is that you quite obviously work on a lot more engines than I do, probably at least double by the numbers you mention in some of your posts, yet you say you have seen no evidence of seepage. I on the other hand would suggest something like half the engines that have been brought to me show some evidence of water damaging bores, and or causing corrosion to valve's and seats on one or more cylinders. Trying to understand why this may be the case and what is a reliable solution is the thrust of my discussion. One thing I have noticed which may have a bearing is the condition of many NZ blocks, corrosion seems to be more of an issue than I remember in the UK, it is not uncommon to go through into water jacket with just a +40 rebore. This I believe may be because with our warmer climate very few (particularly North island) cars have been used with antifreeze or any other corrosion inhibitor, water transfer passages between head and block are often in rather poor condition and may be a factor in why I have found more evidence than you have.