On one of these type of engines in the astra. There is a poss fault on the bore cracking.

We have not had one ourselves but have been warned to test for it when we have removed the head on the one head gasket we have done.

With the cyl head and the pistons level fill the water jacket with water and leave overnight. In the morning if you have a line of rust in the bore you have got a problem.

We were told there is also a uv dye for testing them.

regards ian.