Crankshaft does not rotate freely on an N52 block after a rebuild

Hello,

The engine is an N52B25.

After a lack of oil due to the serpentine belt which broke and sucked and finally clogged the oil strainer I had dead crankshaft bearings I wanted to rebuild the block with main bearing from king racing and a crankshaft from a functional used engine. Having a tolerance of 0.038mm on each bearing I tightened the lower crankcase and lubricated with assembly lubricant the crankshaft does not rotate freely I mean by hand it is not possible, I necessarily use a click in re disassembling several times I find no marks of friction on the bearings. What else do I need to control?

The video will be more meaningful.

It's impossible to tell from the video just how much force is required to turn the crankshaft.

Assembly lube's can be quite viscous (thick), like some greases, and if you're trying to turn it by hand from the nose it can be rather difficult. To eliminate that, I'd suggest cleaning all the assembly lube off and trying to turn it with normal engine oil lubricating the bearings, there should be a notable improvement.

It it's still unduely hard to turn, the three usual reasons are

slightly bent crankshaft - support it by the end bearings and use a DTI to check it's straight.

the block bearing bores aren't straight - you can check that with a GOOD, quality, straight edge. Some use a 1.5 thou' feeler gauge, others some silver paper from a pack of cigarettes, some use a light behind the straight edge. In any case nothing should fit under, or shine from behind, the 'edge.

The bearings are too tight - but you've checked them all, so unlikely.

It's normal practice, least for me, to rest the crank in the block and fit one cap at a time, from middle out, rotating it each time so any tightness will be immediately felt. Some will use a dial torque wrench and note the changes as they should be eaually incremental.

I would second doing one cap at a time and check when it stops spinning. Did you check end-play?

Yes, it is largely within the specifications.

If the crankshaft is bent, I'm not supposed to have different tolerances on the bearings? Can it be the tighter type at the ends?

I checked the crankshaft journals with a micrometer and they are all normal with no ovalization

I don't understand what your second sentence means - if it's bent (which I doubt), it would need to be straightened or, more commonly, the mains' reground next undersize with suitable bearings.

slightly bent crankshaft