Torque converter noise

[sdoyle]

I have just installed a re-bult engine in a E9 3.0 CSA, the autobox was not touched, it has only 40K miles. At first it seemed ok. After a short time, hours, a very loud metallic banging began from the the torque converter / bellhousing area, but only at low revs. When revs increase the noise stops. I have removed the the bottom metal acess plate and plastic cover. The bolts connecting the flywheel and torque converter are tight, it seems as the fly wheel is tight on the crank shaft. I cant see anything wrong, there are no marks on the torque converter / flywheel. With the engine running and banging in progress I can feel a roughness as if something is hitting something else.
Before I remove the gearbox does anyone have any suggestions.
Thank you
Sean.

 

[DougE]

Noise

I have a 1972 e9 with a ZF 3HP from a 1979 528i installed. I noticed the snout that centers the torque converter in the crankshaft was smaller than the pilot bearing hole in the crank. I friend made a special bushing that slides into the pilot hole of the crank and centers the torque converter in the crank.

Even if everything is tight the auto flywheel is very thin (hence "flex plate") and could be allowing the torque converter to move at low rpm's.
At higher rpm's the centrifugal force could be fixing the position of the torque converter and even though the noise stops at higher rpm's the converter may not be centered and as a result it could damage the torque converter or seal.

If you did not have the original engine rebuilt and have access to your old engine you might check the flywheel end of the crank for a bushing.

Doug