EAT6 (AT6-III) torque converter and flexplate noise

[eml]

Hi all,

so suddenly my 508 (1.6 bluehdi 120hp) started making very loud knocking noise, which I assumed to be engine knock at first. The noise mostly happened during idling, but the car was really loud in general. Upon investigation, I narrowed it down to a loose flexplate. I assumed I'd only need to retighten and glue these bolts, but couldn't figure out how exactly is the flexplate locked onto the torque converter. Is it safe to assume that the plate marked in red broke off and is no longer mated to the flexplate? I don't see how else the TC could be fused with the flexplate. The flexplate isn't loose and has no play in regards to the crankshaft.

The TC is free to move by hand and makes the nuts hit the walls (as you can see in the "converter bolt" image), also it has some longitudinal looseness.

I'm working on jack stands, so if I need to drop the transmission it's probably time to give up and book a professional.

Can someone confirm if this is the case here?

[mickthemaverick]

I would think that you will need to drop the transmission to check out the TC properly and would certainly advise the use of a ramp or lift!

[RichardW]

Agreed - can't see there's any option but to remove the box and see what's going on with the flex plate.

[eml]

Thanks Mick and Richard, I've booked a professional to drop the box.

[eml]

Hi again,

Since last time, I have replaced the flexplate with a new OEM one and made sure to torque the flexplate bolts in a star pattern. After some time I had to make a longer drive and ended up having knocking sounds again on my way back. It being a Sunday night I decided to just keep going and be as conservative with the throttle as I can since previously it seemed to be still file under constant load. Anyways, long story short, I got a low oil message, immediately pulled over and turned off the engine. Got towed (ouch!).

The damage: broken flexplate (again), oil leaked out through the oil gallery plug, sheared off torque converter stud. Potentially bearing damage, but I did stop and shut down immediately. I took off the oil pan and could not visually indicate any broken metal shards or broken piston rods...

My question is: where this vibration could come from? I don't want to put a new flexplate and have the same result a few weeks later. Could it be a badly aligned TC, how do I even go about it? All flexplate bolts (to crank and TC) were not loose as I made sure to use thread locker, except the sheared off one.

P.S. what an awful design for the flexplate, everything is just held by a thin metal sheet. I don't think a solid one piece flexplate could have this issue of breaking super easily. Maybe there are some non OEM replacements?