[n00b0rKa]

Hi everyone, and Happy Holidays!

I'm working on my 2005 N52B25 since a few months now, and what started as a quick re-ring has now turned into months of research, reading and a complete engine rebuild. We are talking about an E90 325i which I bought this spring. It has overheated at least once until the amber alert appeared, because of faulty waterpump, which I replaced immediately. The engine ran 3k km after that, without problems. It has done (confirmed at the dealership) 170k kms (100k miles) in it's life, and I tore it down because it was consuming 1l of oil every 300km, although performance was ok and the engine was running smooth.

Long story short, I've finally put my hands on a nice set of micrometers and a dial bore gauge, and proceeded to measure my bores. This is the second time I rebuild an engine, and the first time I measure it, but I seemed to be able to reproduce the measurements and they look really concerning to me:
Cylinder 1: out of round .006mm, taper .002mm
Cylinder 2: out of round .035mm, taper .013mm
Cylinder 3: out of round .028mm, taper .017mm
Cylinder 4: out of round .031mm, taper .016mm
Cylinder 5: out of round .025mm, taper .015mm
Cylinder 6: out of round .027mm, taper .016mm

I only found reference values for new or reworked bores in the service manual, which states a tolerance of .01mm for both out of round and taper. It's important to note, that I measured compression (14 +- 0.5 bar) and leakdown (10 +- 3%, with Cylinder 1 at 10% and Cylinder 2 at 8.75%). I had the cylinder head skimmed and the machinist said it was not warped, the two sides were a little higher than the middle, but nothing scary. The cylinders show minimal score marks, I attached a photo. I measured a few ring gaps and they were worn out of spec.

As you see, my measurements show the cylinders are well out of spec, however the measured values are in no correlation with the leakdown values. I also can't understand why Cylinder 1 is well in spec, but the other 5 are not. I have really no clue what could I do next, as I don't think anyone can professionally hone Alusil engines nearby, and I could not afford it anyway - I planned to do it myself with the Scotchbrite - AN30+felt method.

Do you guys think I could put the engine back together as it is? Do you think the engine's gonna last if I proceed to assemble it? Please help, I'm desperate and starting to go crazy because of this project (which should have been my daily since 6 months now)!

Edit: The black score marks towards the middle of the cylinder are the marks left by my gauge, not scoring.