Noise from bell housing, transmission related...

I have a noise coming from my bell housing.. and only the bell housing, particularly where the flex plate meets the crank shaft. It sounds like rod knock, but not as deep, more metallic sounding. It does it in park, neutral, drive and reverse. The frequency picks up as engine RPM increases. When the engine is cold it can barely be heard, you need to listen for it. However, when the Jeep is driven a bit and it is fully up to temp it gets louder. I can let it sit and idle up to operating temp and it doesn't get much louder. I used a stethoscope on the engine block and transmission and the sound is barely audible on either. I then removed the pointer end and used the open hose and it is the loudest (as far as I can tell) where the flex plate meets the crank. I did notice a bit of run out in the flex plate. Oh yeah.. and I had this same sound on the previous engine, just forgot about it until I got my new engine in... and the people that installed the old engine weren't exactly professionals so they could have possibly bumped or bent something.

I currently have the transmission removed. I saw no real damage on the flex plate, but I did see a ring, like a scratch, on the outer circumference of where the crank meets the flex plate, but it doesn't go all the way through. No real obvious cracks and prior to removal all the bolts were tight. The transmission is currently at AAMCO, which I have heard is fairly decent here. They saw no problem with the transmission pump and the torque converter passed a pressure test(I think that was the test). They recommend replacing the flex plate (which I will any how) and they also recommend replacing the torque converter...

Whats your take? could a torque converter create this kind of noise? Should I replace it?

-Chris

I had almost the exact same sound you described. It was the flex plate cracked at the crank. Had it replaced left the torque converter as is, no more noise.

Did you see the crack? Maybe there is a small crack, maybe that scratch looking thing that isn't very visible...

Take your flexplate off and tap it with a ball peen hammer. If it rings its good, if it rattles/buzzes get a new one