I don't think the power plays into as much as people think.
My point is that there is very little info there. Like I said I have seen zero LLY/LB7 crank failures and about a dozen LBZ/LMM failures in our shop. I do agree power. Has little impact as all of the failures I have seen personally have been stock trucks, although most were heavy medium dutys or tow heavy quite a bit.
I find it quite interesting that I have seen a bunch more failures of one vs the other than the poll shows, that's why I suspect there are more variables that need to be factored in.
Great pics.... Finally one that has the fracture surface that isn't wiped completely out, & someone that can take a picture:thumb:
Anywho, the crack starts in the rod journal fillet (bending fatigue maybe some tortional fatigue). The beach marks (fatigue fracture) radiate away from the crack initiation site (like ripples in a pool of water). These are slow growing cracks, very smooth. The rough part brittle, ductile (final fracture) part was just to weak to hold any more. I can't tell from the pics but you should be able to see Ratchet marks in the fillet where the crack began, with the beach marks radiating away. Last pic also shows what looks to be a possible inclusion very close the surface of the rod jouranl fillet, but could be just the lighting.
I have suspected improper grinding of the fillets on the crank. It makes no sense why some live at 1700 hp (Dimitri) and some die at stock power levels... Unless there is a issue with the manfacturing (finishing) of some cranks.
Anyone know if all the cranks are made at the same foundry & finished by the same machine shop?
Bhoward, you want to cut the broken ends off and send them to me? Anyone else that has a broken one that wants, can send it to me as well. Id like to get several of these together and compare... Maybe let some of the Cat guys take a look and help shed some light.
My point is that there is very little info there. Like I said I have seen zero LLY/LB7 crank failures and about a dozen LBZ/LMM failures in our shop. I do agree power. Has little impact as all of the failures I have seen personally have been stock trucks, although most were heavy medium dutys or tow heavy quite a bit.
I find it quite interesting that I have seen a bunch more failures of one vs the other than the poll shows, that's why I suspect there are more variables that need to be factored in.
Absolutely, When I pull the rest of the crank, I will pm you for your address and send you the cut off pieces.
It would be nice to try and chase some answers down with out any ulterior motives clouding the results.
No doubt! I unfortunately don't get much chance to do any investigation as I spend most of the time trying to get the customer covered under warranty. Any answers I get from GM are usually clouded in legal bs, like it was on "fire" isn't an acceptable term but experienced a thermal event instead. Which bring the new description, a thermal event with visual indicators!
Yes, its long gone......
really? i remember seeing it at todds not long ago...damn
I think he still has them, he just opened his own place like last week