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Bone stock 2016 LT1.The history was it was a car another dealership tried multiple times to get it to quit leaking oil since I can see the previous warranty repairs. The owner must have got tied of it and sold it or traded it in. The current owner did not know of the history and brought it to us for oil leaking. It was everywhere we cleaned it up and drove it seemed to be from the front cover. Replaced it and came back over an over until we have replaced several seals and gaskets. Finally tore the engine down and found this. You can feel these stripes they are terrible also feel like 240 grit sandpaper and causing so much ring seal problems crank case pressure it's pushing out oil from the seals.
EDIT zoomed in on the pic and its definitely a factory machining screw up. Never seen anything like that.
Last edited by gearheads78; 06-27-2018 at 01:28 PM.
That explains the leaks. The magnified lines are the boring bar cuts. For some reason the honing stones never touched that stripe in the cylinder. Weird. The rings got so filed down that there was little to no seal on that (maybe more) cylinder. Blow-by pushed the oil out anywhere it could go. Had to be down on power. I’d imagine oil temp was up also.
These are built by robots, so QC is spotty at best.
Even though he's not original, I would hope the owner would get some satisfaction from GM, given the dealership repair history and that this is clearly a factory f-up.
Bad calibration on the boring process. The hone didn't have a chance.
Carbon/oil on the piston tops is very normal. Even more so with poor ring seal. That would create a tremendous amount of blowby that gets sucked in by the PCV system.
06-26-2018, 06:22 PM
Anyone ever seen this LT1 cylinders? 
