Are my M20 Pistons Okay?

[ManWhaleA]

Hi guys, I decided to do all the maintenance of my newly acquired bmw e30 after passing its smog test. I was checking the pistons of the M20 and saw that they looked damaged and scratched. It ran perfectly fine before dismantling the engine, but I wonder if they are okay?





Thanks.

[noid]

What you're looking at is the factory cylinder cross hatching. Its a good thing to see, it means your cylinder walls aren't too worn out.

In the first picture, the light colored spots on the cylinder walls, is that from the camera flash bouncing off the piston?

[SkiFree]

Before you took apart the engine, what were the compression/leak-down results?

None of us can say definitively if your pistons are "ok". Are there cracks we can't see? What do the bores measure to? Etc. Only way to have %100 piece-of-mind is to have it checked out by a machinist. Anything short of that is just guessing.

[Cayoncrusier93]

What skifree said! I had a block that had cross hatching and compression around 150 on all the cylinders, took the block in to machine shop, cylinders walls were tapered and needed to be bored over to remove it. If you want to do it right, take it in. If not, build it and regret it just like i did when it started burning oil.

[TobyB]

Can't tell until you take them out of the bores and inspect and measure. As everyone's said...

What prompted head removal?

That's not usually considered 'maintenance'...

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