Engine REALLY does not want to go in...

[aresfiend]

Today we pulled the remains of the M50B25 from my car and went to install the freshly built M50 with M52B28 internals.

The first time everything went exactly as planned. It slid in relatively easily and within a couple of hours from starting it was mated to the bellhousing of the 4L30E. But I couldn't turn the crank to attach the flex plate to the torque converter. I mean the crank REALLY would not turn.

The confusing thing about this is that I was able to fairly easily turn the torque converter to line it up with the flex plate, but it seemed too far away from the flex plate to get bolts in. We pulled the engine back out and inspected everything. All the dowels on the block are fine, the flex plate assembly was done correctly, torque converter was properly installed in the transmission, so we tried it again and I had the same issue.

I genuinely cannot figure out what's going on with it at this point. There's something small I'm missing and I need an idea. Either that or something is completely dusted and it's just not visually apparent.

Also, before "why don't you just manual swap it?". Current financial restrictions but me needing wheels are kinda what's going on here. I have a 2.8L M50 engine and an automatic E34 without an engine.

[m735is]

Was the rebuilt motor originally an automatic?

[whiskychaser]

No disrespect but you did put the spacer behind the flex plate? Assuming the engine is out, can you turn it over by hand now?

[aresfiend]

Was the rebuilt motor originally an automatic?

The only parts on the "new" motor that aren't off this car originally are the crankshaft, rods, pistons, and block. As far as I was told the rotating assembly is off an E39 528i also with a 4L30E but I wasn't the one to remove it.

No disrespect but you did put the spacer behind the flex plate? Assuming the engine is out, can you turn it over by hand now?

I did actually double check the spacer position, it's in the middle just as it came out (flex plate on block, spacer, torque converter mount). Everything is also properly aligned on the dowel at the back of the crank.

Engine spins freely when it's out.

I did just want to edit to add, I've literally never separated an automatic transmission and engine. If the flex plate order is wrong I won't be surprised.

[flynfrog]

You should have to pull out the TC to meet the engine. This gap at least on the larger GM transmissions is 3/16" with the TC fully seated. Did you swap over the old flex plate if not are you sure they are the same. I would figure out why the engine wont turn over. check the bellhousing and see if the flex plate it interfering somewhere. You should be able to mate the trans and engine out of the car and stab it in all together.

[aresfiend]

I cannot get the torque converter to move forward at all with the engine in. I did swap over the original flex plate. I checked around the bellhousing and I can't see if it's hung up on anything, but it appears to have plenty of clearance from what I can see through the starter hole and the larger hole at the bottom of the trans.

[aresfiend]

We figured out the issue. My brother and I pulled the engine out and I decided to remove the torque converter from the transmission to test the fit. It did not go in.

The crank from an "automatic" 528i has a pilot bearing in it, or part of it anyway. The outer race is chilling in the crankshaft. Someone had previously managed to rip the inner race and bearings out but somehow smash the outer race in there even further to the point where it barely blocks the TC pilot. Luckily it's still out far enough I'll be able to get a bearing puller in. I don't know how I didn't catch that, but I've never had part of a race so far in that it barely blocks the TC from entering in.

[whiskychaser]

They say clean out the hole where the TC fits and apply a little lube. But that does not usually include looking for the remains of a pilot bearing. Well spotted.