Hello all, first post by big time lurker.

I'm am hoping that somebody could shed some light on some issues I am having..

I am pretty sure I have the classic flexplate knock. Checked the bolts today but they seemed pretty tight, didn't see any cracks either. (could be though, never know.)
But when I moved the plate slowly with a screw driver I could hear something touching something albeit not super obvious since it was turned by hand. Only every other turn. On start up there's the classic "dude in the tranny with a sledgehammer-knock"

So, what goes on in there, what could be making the knock, in the flexplate area?

XJ-91
4.0 auto
Otherwise running fine.

 

I had the same problem about a year ago. I took the tranny out and check the flexplate/bolts. Didn't see any cracks but, they were there. I didn't see them until it was on the bench with a magnifying glass. They were hair line cracks around the bolt holes. Hope my experience helps.

 

The center section of the flexplate will crack and will be hard to see.

 

You might pull the top starter bolt and see if the end is burnished from touching the torque plate. Starter been worked on?

 

Thanks for the input!

Assuming it's cracked, wouldnt the bolts have caused it and be loose? (Pardon my ignorance)

I'll have a check at the starter but it's not been when worked by the looks of it. (Oil)

 

I have enough endplay in my crank, t-plate would hit the bolt harder when I gassed it. Until I found it I thought I had big trouble. There's still a stack of washers on that bolt right now.