I'm half way through replacing the clutch in my 07 FXT and have run into a problem I haven't experienced before. The car was running perfectly Friday morning before we started. We jacked the car up then dropped the gearbox and removed the clutch and flywheel.

I installed the new flywheel I attached a dial indicator to check the run-out and I started turning the engine over by hand and it suddenly hit a hard stop. I realised I had rotated the engine backwards, I then rotated the engine forwards but met the same hard stop in the other direction. I did this a couple times but could only get it to rotate about 350°.

My only thought was I must have done something to the timing and the piston is hitting a valve. I removed the timing cover and I double and triple checked it but timing was fine.

I took the flywheel back off. No change.

The car was due for an oil change so I checked the oil level and it was barely on the dip stick but the engine does have several oil leaks mainly from the valve covers. I dropped the oil and it was quite black but no glitter.

I then removed the spark plugs and scoped the cylinders. The resolution is quite low but couldn't see any marks on the piston face or any interference with the pistons.

I then removed the timing belt and found all 4x camshafts rotate smoothly when not opening a valve. I set the camshafts so they were rotating freely which I believe isn't opening any valves. I then turned the crankshaft from the crank bolt but found it stiffer to turn than I remember it should from years prior and it still hard stopping.

I am stumped and very frustrated at this point.
Is there anything I've missed?
Can you guys offer any advice?