Noise after clutch install

[MrNoah]

EDIT: The problem was a bearing retaining clip (?) near the right axle pinched in between the block and the bell-housing and rubbing the flywheel. Installed correctly and it's running great.
I would delete this, but I'm not exactly sure how. So, if a mod wants to, please do. Cheers, guys!

First off, this is a great site and I've found the forums and articles very helpful. Thanks, guys!

Now, I've got a problem. I just attempted a transmission rebuild and a clutch replacement, and after getting everything back together my 2002 base cooper (5-speed r65) is making a high-pitched whirring whining noise that seems to come from under and behind the engine. It definitely sounds rotational and mechanical. (Not an exhaust leak)

It makes the noise moving and stopped, clutch in and out, in and out of gear, and the noise changes pitch with the engine speed.

To be sure it wasn't anything belt driven, I removed the belt and started it. Still there.

I then removed the starter to see if it was not disengaging. Still there.

It was a long shot, but I disconnected the power steering pump. Still there.

Since the noise is there when the car isn't moving, I have ruled out the output shaft and drivetrain thereafter.

Since the noise is there when the transmission is in gear and the car is not moving, I have ruled out the input shaft bearings.

Since the noise is there when the clutch is disengaged and also there when the clutch is engaged I have ruled out the clutch.

I thought it might be the throwout bearing, and I removed the clutch linkage to remove all pressure from the clutch arm. Didn't change the noise at all.

This one has me puzzled! The noise wasn't there prior to removing the transmission, and I haven't touched the engine with the exception of replacing the engine mounts. The oil is full and looks clean. The coolant is full and looks clean.

I did lift the engine by the oil pan, but I used a board to distribute the weight and nothing looks damaged at all.

Does anyone have any thoughts? I would greatly appreciate it!

Thanks in advance,
Noah