M20 E block, one bad piston

[NbAmTwE]

So, I'm gathering parts for an e30 I bought to be a fun weekend trackrat/mess around car. I have an 86 325e and will be doing an I swap on this block. I pulled the head today knowing I might see one issue, the PO bondo the radiator a bunch and I found some of that residue in my coolant hoses and fluid. So, when I pulled the head off here is what I'm having to work on...






and...



I'm sure this last one is okay, all the other are fine; no damage to pistons and valves look okay to use but I won't be using that head.

So help me out guys, I know I need to send my head off to a machine shop when I receive it to make sure it's not warped and what not. Should I go ahead and send the block as well to be cleaned up and will I need a new piston or is that fixable. It may be hard to tell from the pic, but this seems to be the result of some bondo running through the coolant passages and some leaking into this cylinder. Any advice is better than what I would know.

[Myster-E]

I dont know how bondo got into your radiator but its not gonna leak into the cylinder and cause that. that looks like water that rusted the cylinders and pistons. You might be able to salvage the pistons. pull it apart and inspect the cylinder walls to see if its even worth using that bottom end. Otherwise, I would just get another eta bottom end. they're cheap

[NbAmTwE]

that's what I was thinking when I saw that, I'm pretty sure I know where an eta bottom end is just laying around in my town.

[MTechnikII]

aren't those pistons made of Aluminum alloy? they shouldn't rust, at least not like Iron.
Henry

[lolcantturn]

That is the strangest thing I've ever seen

[billybobjoseph]

I'm going to have nightmares because of that pic