Opinions On This “Line”
 

Im reassembling my motor and noticed this.(see pics)
Any ideas on this straight line on the snout of the crank?
Ive never see this before.
I sent this pic to my machinist. His response is that it’s not a crack Cracks dont create a straight line.

Looks like a stress crack to me. Maybe your machinist doesn’t want to admit he missed it? I’m not sure you can drill a small hole at the end of the crack to create a termination point, kinda like glass. Not sure. Hope others will chime in.

Can you feel it? Could it just be a stain from the keyway slot in the crankshaft timing chain gear?

I'd drill a tiny hole in the end of the crack as suggested above, and run it. Unless you are using it for direct drive on a procharger, it will likely look the same if you take it apart again in 10 years.

To me it's hard to tell from the photos. It could be a mark from when the key slot was machined or a crack. Personally I'd get some crack checking dye penatrant and it should reveal more.

Is that on the drive side of the keyway or the back side? I should know by looking, but I don't :)

Back side
 

Since the crank rotates clockwise, it's the back side of the keyway.

Timing gear had a burr to write that line. No worries.

Pull the key out, shine some light in there and take a pic at like a 45 degree angle toward that area.

Looking at it from the top with those pics it's hard to tell if it's a crack or just a groove/step.

The key looks a little beat up on that side too, almost like the balancer was loose and hammered it.


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I would check it with dye penetrant as suggested below. Or tape off the bearing area to protect it and see if a shop can mag particle test it while it’s assembled. If I was going to hammer on the motor I would want the peace of mind.

I like the dye suggestion, makes total sense....


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Sorry, for the late response. Took the crank back to my machinist and he looked at it. Not a crack but a groove from the harmonic balancer.