My 82 F-150's c4 has a knocking torque converter that i cannot figure out. The flexplate to torque converter nuts are all tight... but it sounds like its wobbling on the input shaft, and randomly makes contact with the bellhousing, or some other part of the trans. It can be heard and felt inside the cab.

It does this only at an idle, regardless of what gear it is in.

Anybody have any suggestions?

 

Sometimes the flex plate will be cracked. When the engine pulses hit it, it will pop or knock. If there is significant flexing it can hit the bellhousing. This problem only gets worse and ultimately will fail with at best minor damage, at worst, trashing the tranny, maybe the firewall and maybe the engine. Best to figure this one out quick.

You might be able to check for cracks by pulling the splash plate and using a strong flash light to look at it to check all parts. You will need to turn the engine by hand or extremely carefully use a bump start switch. Naturally use safety precaustions to prevent the engine from starting.

I have never seen this problem and am no expert but I have read about this problem in magazines and I think this forum.

Good Luck,

Jim Henderson