“I heard it’s possibly a tolerance issue at the crank shaft”
Here’s some trivia, not really related to the Toyota problem, that a aircraft engineer told me.
Pressure-lubricated sleeve bearings, such as crankshaft bearings, don’t wear once up and running because the shaft is floating on oil and not touching the bearings. Wear only occurs at startup when the shaft is resting on the bearing and before the lubricant film gets in between.
Spent 37 years in aviation maintenance....in contrast to autos it’s a different animal all together.....obviously.
The tolerances are way tighter in many places.
e.g. one engine I worked on had assemblies that one side was designed to spin, the other side was static but the two needed to seal so there was no oil leakage. The flatness required to accomplish the “mechanical seal” between the two had to be in the millionths of an inch range.
To accomplish that the parts would require a process called “lapping” which is basically making the part flat.
To verify flatness the process was to measure using an optical flat that shows light bands.
Anyway, yeah things are a lot tighter in aviation.
I won’t bore you any further with light bands thing but if your at all interested this explains it.
https://www.kemet.co.uk/blog/lapping/how-to-measure-flatness-technical-article