Flexplate/Torque Converter or Harmonic Balancer?

[Dancing Bear]

Good ol' Blackjack (my 02 GTP) is making a noise.. I went 3/4 throttle down the road to get to my chorus performance on time, and when I pulled up to the parking lot I could hear a knocking/banging sound. Limped the car home, got under it searching for what I thought was a rod knock at first.

Probed around with my stethoscope, discovered the noise was coming from the bellhousing. Removed the inspection plate and rotated the crank slowly while my mechanic neighbor inspected everything. After multiple rotations and a very thorough inspection, we found no cracks in the flexplate, but we did discover that the welds on the torque converter have a small crack in each of them.. They don't look very deep, and they're not very long, maybe 3/4 of a inch

While the engine is running, if you rev the engine the whole assembly will shift back and forth (~1/2in). The noise increases in frequency as you rev the engine up and down. Car is slower than normal to turn over, but fires right up. Oil was changed and had no chunks/glitter indicating a bad bearing.

I'm assuming the slow crank is from something dragging on the inside of the bellhousing or on the serpentine belt drive

My neighbor who was a mechanic for many years mentioned that these cars are notorious for having bad harmonic balancers, which could cause this issue and the noise would travel down through the crank to the bellhousing

Any ideas are, as always, very much appreciated!

 

[CrazyGuy03]

Without looking at it, sounds like a flex plate issue.
The harmonic balancer look ok to you? Any wobble?

 

[Scottydoggs]

post a vid.

let it idle some, then raise the rpm's to like 2500, then drop the throttle and let it drop back to idle on its own.

a rod knock gets worse sounding with rpm's, a busted flex may stop with rpm's.

if it was the balancer, you'd hear it from the pass side. id still look for a crack around the rubber to the metal part the belts on.

you can also pull your oil dip stick, see if theres any glitter on it.

 

[Dancing Bear]

I put my stethoscope all around the oil pan and heard nothing, drained the oil the day after this happened with no flakes or glitter anywhere inside it. I even swept around it with a magnet and got nothing.

The knock definitely gets worse with RPM, but like I mentioned I probed everywhere with the stethoscope and the noise is most definitely coming from inside the bellhousing area

 

[Scottydoggs]

keep in mind bearings are made of copper. not magnetic. best to drain your oil through a rag or coffee filter. that way you can see if theres any metal.

cracked flex plates are hard to see while the engine and tranny are bolted together.

a vid would still help the most. we kinda need to hear it. or its just guesses and nothing more. you can move the camera around the engine where it sounds the loudest.