'01 530i engine knock
A co-worker of mine purchased an '01 530i with 33K at an auction, sight unseen, with an unknown history. When it arrived at his house he discovered it had an engine knock coming from the rear by the oil pan.
He's done the following in an attempt to diag the problem:
- Disconnected the torque converter and ran engine - no change in knock
- Pulled plug wires one at a time with engine running - did not differ/cyl
- Pulled all plugs and cranked - no knock
- Pulled engine and checked main/rod bearings - nothing obvious
At this point he's thinking a wrist pin or perhaps a cracked piston skirt. Are there any common failures for this particular engine? Anything else he should check?
Thanks in advance for any input!