does seem the crank snaps in the same place each and every time , did u ever get chance to read that full engine report of where that guy had his engine inspected after the crank snapped
Yes possibly. Was this were his investigation found that the filet radius wasn't correctly formed? If so then yes I read the report and would have thought the same thing myself. Crankshaft failure can attributed to a few factors. However with modern materials and manufacturing techniques, it really shouldn't happen.
The very fact that all these crankshafts fail in the same place, in the same way, shows there's a definite manufacturing fault it that point.
The filet radius is a vital part of the crankshaft, as it reduces the chances of cracking across the journal. Years ago crankshafts were made of cast iron, which was then machined to the required tolerances and bearing dimensions. Where the crank web meets the journal, large rolled filet radii were used to eliminate stress raisers.
Most modern crankshafts (including the TDV6) are forged, so are inherently more robust than a cast iron cranks of old. However stresses can be formed between the crank pins and webs, due to uneven and rapid cooling of these parts in the forge pressing. To eliminate these stresses, the journals need large filet radii, basically smoothing out any potential stress raisers, increasing crankshaft life.
as indeed all reports have found the shells spin, blocking off the oilways and crank consequently snaps
The shells spinning is something different, which is resulting in a couple of possible scenarios. A the bearing spinning in the rod simply makes a horrible noise before the engine is stopped and investigated. The second scenario is the bearing spinning in the rod causes friction. The friction can be high enough to weld the rod to the crank, using the bearing as the filler material. In this instance the crank can stop rapidly, causing it to snap, or the rod to break.
The question is. What is making these bearing shells spin? And what can be done to prevent it.
It's a complicated thing this catastrophic engine failure, but on that shouldn't really happen at all.