Finally got a chance to tear down my Series I L24 with 186K miles for excessive oil consumption (300-400 miles/quart).

 

All in all things looked remarkably good. Crank and rod bearing show wear in the expected places but the crank surfaces are within a 0.001" with not taper or feel-able grooving. 

 

Cylinder walls have little to no taper and are round to size within 0.001".

 

Cylinders 1,2,5, and 6 are clean with some crosshatching visible.

 

Cylinders 3 and 4 are smooth but show the artifacts in the attached photos. Since it is hard to get a finger nail or ball point pen at right angles to the surface, I felt the surface with a clay modeler's tool. Most of the artifacts surface cannot be felt with the probe. In fact the only artifact I can feel is one running parallel to the bore and it is about 0.001" higher or lower than the adjacent smooth surface. (can't tell if it lies on the surface or into the metal.

 

Can anyone identify what these artifacts are? From what I know, the car may have sat in a garage for a year or two. Since cylinders 3 & 4 move up and down together, I suspect they were sitting in the down position during that time. 

Never heard the term artifacts when it comes to engines. Sorry but not sure what the marks are from.

I just broke down a ZX motor with 110K miles and couldn't believe how well it looked. The pistons cleaned up like new.

Water stain lines from a previous bad HG?