difficulty turning crank during engine rebuild


New Member
Jun 1, 2021
Quick history: Bought a 2013 535xi with a spun bearing. Just the tabs on the bearings were flattened and so the bearing was spinning inside the connecting rod. The bearings had not overlapped. Originally tried to just swap bearings with light sanding of the journal but it appeared the knock had gone for too long. We thought it was still good because it only knocked at a certain rpm... can't remember right now.. believe it was at around 2500 RPM. Have had good success with that previously on an N54 but that bearing was swapped the same day it knocked. This one, the journal was questionable but also the connecting rods were roasted black.... and god knows how long it was knocking for. Gave it a shot anyways and without a surprise the engine siezed within a few hours of swapping the connecting rod bearings...

Fast forward, I purchased a used crankshaft (measurements seem okay and journals look good without any sign of spun bearing.) I took the engine part (removed head, pulled out pistons, etc) and during bottem end assembly I noticed the crankshaft wouldn't turn. I was able to get it to turn and it seemed fine until is stopeed and tried again after 5 minutes. It siezed up again. This is with the block on an engine stand and without the pistons installed. I did some in depth research and read some threads talking about the bed plate alignment.. it seems either that is my issue or the assembly lube I am using causes this seize like feeling which I read about too ? Also something about line horning? All that said, I read opposing comments and seen other on youtube assembling it without any of those things without issues.

Wondering if anyone has ran into this issue with the N55 or N54 motor ? The block does have the dowls in place so I think the bed plate alignment is okay... to the human eye precision anyways. I have already plastigauged clearances and double checked the bearing thicknesses... tomorrow I plan to retry assembly with regular motor oil to see what happens.... As mentioned, I read some forum discussions of assembly lube requiring crazy amount of torque for the initial spin.

I should mention once I am able to break away that initial seize like feeling, the engine turns okay. When it is left for 5 minutes, then it seems like it has seized again and I have to untorque part of the bed plate to get it to turn again... and turns fine again after torquing.... until it is left for another 5 minutes :/