So I have a 2000 WJ (4.0, 42RE, NP242) parked in my driveway that I want to get rid of... (belongs to my father in law). He bought the jeep with a blown motor with the intention of a motor swap.

Soooooo. We took the motor out, and put another 4.0 in, lined up with the transmission and bolted them together. We had hard time with lining them up originally and finally got them to line up, tried to bolt them together and it was tough. When we were trying to line up the flex plate to the torque converter. It was so goddamn tight that when we turned the crankshaft, the flex plate also turned along.

We decided to take the motor out and took the torque converter out. Took the transmission oil pump out and it was damaged, so we ordered another one off eBay.

Today we put the oil pump back on, then the torque converter back on. We noticed that the torque converter won't spin freely by hand.

Now I'm not familiar with 42RE but I assume it should spin freely.

So my question is, is the torque converter supposed to spin freely by hand while mounted on the oil pump?

It is reasonable that there would be rotational resistance when attempting to turn the torque converter.

There are three concentric drives at the torque converter, the input shaft, the stator and the oil pump. The oil pump is driven by a pair of exposed notches in the end of the torque converter shaft. Those drive the ears in the oil pump. The oil pump should rotate w/ minimal resistance.

The stator and the input shaft will both present rotational resistance, due to the clutch discs and frictions in the transmission.

The flexplate is bolted directly to the crankshaft and SHOULD turn with it. The only thing driving the torque converter is the 4 bolts that lock the converter and the flexplate together. The converter should be mounted in the transmission first and be engaged with the oil pump BEFORE the engine is put in. You apparently crushed the pump drive dogs and you may have bent the trans input shaft.

When you put the converter in, you must be sure it's ALL the way in. You can measure the distance from the engine bellhousing flange to the back of the flexplate, then the distance the converter bolt bosses are from the trans bellhousing flange. The converter distance should be about 1/4" MORE than the flexplate distance. If it isn't, the converter isn't engaged with the pump. You can spin it back and forth rapidly until it does.

Once the engine is in, make sure the converter spins by hand before you tighten the bellhousing bolts. Done properly, the engine should slide together over the dowel pins.

With the engine out, you should be able to spin the converter easily by hand. There is one other thing. If the engine was standing on it's flexplate on the ground, it could have bent the plate.

Thanks.

Apparently he overtightened the oil pump on the transmission. He went and loosed them up & torqued the bolts correctly and now all is good.