I’m having a strange problem with my recently rebuild engine. It’s the original cylinder-head of my S2 1969 cabrio. The car has driven around 200 miles since restoration. There were no problems in the first miles but right now a very small leak has been seen in the casting of the aluminium cylinder-head. Quit typical is that the leak is right beside a coolant core bolt, but it is not coming from the bolt or copper washer. The coolant is coming really from the aluminium casting. See photo’s below:
So my biggest worry is that my cylinder-head is cracked. Is this likely or would it be a corrosion problem? Or maybe something else? All suggestions are welcome!