Quote:
Originally Posted by former 240 s14
We found the full culprit of the failure, Main Cap 1 bearing failure. It only partially spun then blocked the oil feed to the crank causing the over heating issues to cylinders `1 & 5. The main journal cracked so the block is toast.
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The million dollar question would be, what caused the new oem main bearings to fail after only 14k miles since the rebuild?
I am not convinced the failure would be due to oil starvation. I think it's much more likely the rebuild was done poorly, there is a specific procedure to select the correct main bearings to use when doing the rebuild.
I know you said the PO did the rebuild, but it would be good to know what shop did it, and perhaps even reach out to do them to ask if they selected the correct main bearings based on BMW documentation, or did they just throw random main bearings in there.
IMO, after the first main bearing failure, it is still possible that the oil cooler, lines (or any other parts from the failed engine, vanos, oil pump, etc) were re-used and not cleaned / rebuilt properly which contain debris from the previous failure.