Pitted EJ25 Piston Wall - I need feedback please

[545ier]

Hi all, first off, thanks to everyone for sharing your conversions. I've picked up a lot and have been inspired to take on the challenge of putting an EJ25 engine from a 98 Legacy into my 73 Super Beetle.

I am currently tearing down the EJ25 to replace gaskets, timing belt, bearings etc... I'm at a point where I need to determine whether or not I continue with this short block and figure out what my options are or find a replacement. In my opinion it looks pretty good overall and the engine itself has been cleaning up rather well as I go along.





Problem: Pitted Piston Wall.
Root Cause: seems like the head gaskets were blown and caused coolant to enter the piston, which lead to pitting the walls.





I have not removed the pistons yet but that will be my next step, to determine if there is any damage to the piston itself.

My main question is... Would I be able to oversize the pistons, without having to machine the valve head? I'm sure a local machine shop would be able to give me an answer but not everyone deals with machining Subaru engine blocks (at least the shop that I go to here in North Jersey does not)...

With that being said...
1. What size/brand piston would you recommend?
2. Can I increase piston size without machining the heads?

[Piledriver]

You have some minor rust pitting.
Depending entirely how deep this is, it can be no problem >shorten ring life some.
If the pits are not too wide, there may be little worry at all.

Having said that those aren't the nikasil bores are they?
If that was the case the answer would be find a new block.

[billz60vw]

that block is ok to use. you will have to get it honed and use some oversize pistons. i vote for cp pistons or if you dont plan on to much power manley or mahle..

[545ier]

You have some minor rust pitting.
Depending entirely how deep this is, it can be no problem >shorten ring life some.
If the pits are not too wide, there may be little worry at all.

Having said that those aren't the nikasil bores are they?
If that was the case the answer would be find a new block.

Thanks for the info Piledriver. I confirmed with another machine shop that it can be bored/honed without a problem. The pitting would've bothered me just knowing that it would've eventually needed fixing...

that block is ok to use. you will have to get it honed and use some oversize pistons. i vote for cp pistons or if you dont plan on to much power manley or mahle..

Thanks for the info billz60vw. I didn't plan for any additional power increase since it'll be a world of difference going from a 36hp engine. On that note... I went with CP pistons anyway.

[ryans88gt]

Did you perform a leak down or compression test before you pulled it apart? I had one cylinder that looked similar maybe not quite that bad. leak down and compression were prefect, so I just gave the area a light scuff with a cylinder deglazer and left well enough alone. Engine runs great.

[545ier]

Did you perform a leak down or compression test before you pulled it apart? I had one cylinder that looked similar maybe not quite that bad. leak down and compression were prefect, so I just gave the area a light scuff with a cylinder deglazer and left well enough alone. Engine runs great.

ryans88gt I did not perform a leakdown or compression test. The moment I saw the pitting and rust associated with it, I couldn't ignore the damage that was already done. The minor pitting could have turned out to be just fine but I'm also certain that the pitting would've been filled with oil deposits which in turn, would burn oil in the process (oil consumption), which would possibly lead to carbon buildup/failure of valve seats/stems/seals, smoke out of the exhaust... etc... not worth the headache or another teardown just to fix the problem at a later date. Better safe than sorry in my opinion.