We have the l76 pulled apart from my brother Pintisc G8 to remove the afm stuff and do a cam swap while we are at it. The engine only has 39xxx miles on it so not very worn. Cylinder number 1 has a couple visable vertical marks in the liner on the underside of the cylinder. If you go slow enough you can feel it with your nail. What would have caused this? Could have been there since new? He's never noticed any oil burning issues and the car ran strong before we did the cam swap. Those engines are known for afm lifter issues which is why they are coming out, but none of the lifters look scorn or have any signs of being on their way out. Should we just button it up and call it good or does this mean we are now expanding the scope of this cam swap and pulling the block?

 

No idea on the cause but it look pretty mint to me. I don't see how something that can barely catch an edge will grenade the engine.

I'd slap that sucker back together and let it rip.

 

I pulled apart a 6.0 with 250k on it and it looked like that just not as circumferential maybe half as much, could still see crosshatching in the cylinders. Didn’t even bother to hone it just wiped down the walls and oiled them. Runs just fine with no issues.

 

Are you worried about the light scoring from the piston moving up and down or what looks like oil that sat in the rings for a bit?

I don't think either are a problem. That's carbon that would be blown out very quickly on start up. Try turning the engine over to see if you feel it as the rings pass by it. Be warned... some gen 4 engines down have a timing dot on the lower cam gear... be aware of that as you turn this thing over and play with it.

 

The light scoring is what I'm worried about.

This motor does have the timing dot on the lower timing sprocket. We planned on replacing that sprocket though since the timing chain and upper sprocket are being replaced, it is keyed to the crank so we shouldn't lose our timing reference right?

 

glaze breaker or honing brush time if you are really concerned

 

Yup the timing gear only goes on one way.

 

Thanks. Never had a engine apart before so I'm learning as I go with this. I just have a bunch of tools and far too much confidence haha

 

The Lines in the cylinder are usually caused by sharp edges on the ring ends. These engines are massed produced and the parts are assembled as is. They don't do any clean up or hand fitting like a custom engine would get.

It usually doesn't hurt anything.

 

You could always do a light hone with a ball hone.

Personally, I wouldn't worry with it.