To properly check this you need to use a magnaflux. Those cracks in a cylinder wall can be very hard to detect. You can find most with using a talc. After cleaning the cylinders and getting them dry you hit the walls with talc powder and it'll gather in the crack and expose it.

The mechanic says that the crack was caused from inside the cylinder. A valve must have broken and hit the side of the cylinder. It is hard for me to imagine that this impact would have caused a crack to form through the cylinder wall all the way to water jacket (I would have expected more visible damage on the inside of the cylinder) but I guess anything is possible. I am attaching pics for opinions.

The crack is vertical and all 3 pics are of the same "crack"

A part of a valve would not cause an outward crack. It would have caused impact damage on the piston and head.

Are the damaged valves from the current new-ish head? .. . or from the previous head?

Previous head

Oh yeah, that'* right. You didn't buy new pistons for this car. I suspect because your "mechanic" probably said they were fine or at the least didn't tell you they were needed. With damage like that, pistons were needed, and still are.

I think I see the crack in the pictures, but there'* some scoring as well. The top of the bore looks pretty beat up, too. Based on what little I can see, it looks like this block would need to be bored and honed to solve everything except the crack. The crack condemns the block unless you want to put more money than the car is worth into repairing it, and then have your "mechanic" ruin it anyways.

After boring it, you'd need new pistons as well.

I don't know if this block even can be bored safely, but thanks to the crack, it doesn't matter anyways.

It'* interesting that the crack happened so low in the bore. Usually they crack closer to the head.

I'm not sure if I see a crack or scratch. If that engine dropped a valve I would expect scratching and damage to piston and head.

Yeah, that'* where I am with it. I think I see what jungloverano is talking about, but the pictures don't catch it clearly enough. There are a couple of other vertical scratches there too, so maybe I'm looking at the wrong thing.

Either way, it there'* a crack anywhere in that block'* cylinder walls, let alone way down low where I think jungloverano is indicating, the block is scrap as far as I'm concerned.

CathedralCub, are you assuming new pistons are needed based on general damage or is there anything particular damage you can see.

I would have thought anything that causes a hard enough impact to crack the cylinder wall would leave more surface damage than what I see.

This car with this engine did run well after the repairs except when engine was turned off and water started filling the cylinder.

This person claims JB weld worked on cylinder wall for years ? This is hard to believe for me . Anyone have an opinion on this type of repair..