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So I've recently got my car back running, but now I'm about ready to pull my hair out. The car is making a weird vibration at idle, almost like a growl... not really audible, but more of ax feeling. Seems to do it more when the transmission is up to temp (th400), feels a lot like loose bolts on a torque converter.... but the bolts are tight. I've never experienced a bad torque converter, so here's the question. If it were a bad torque converter, would the vibration go away once the car is put in reverse? I've wrestled with this, because the converter is a constant, but I'm really at a loss. The car drives fine, stall characteristics haven't changed (9.5 PTC 5200 true stall speed). Only 2 things I've changed since I reinstalled the motor are the passenger side motor mount and the transmission mount as it was destroyed (didn't use solid mounts). Any suggestions? Oh, and one more thing, the feeling seems to change, depending on steering input. If I weave to the left, it intensifies....to the right almost disappears.
Ok so my experience with a bad torque converter felt more like the trans needed rebuilt in both cases. Half the reason I have a advance auto gm55 converter in mine is because I thought the trans needed rebuilt and the converter was a shot in the dark. Mine showed issues under lock up. It would have a vibration when it slipped under a light load on the 3/4 shift and locking up. But when I got on it on the highway it would free rev, or I could manipulate it to grab but it would always slip once power came in. My gmc 2500 would also vibrate under light loads like going up a hill.
Neither made any noises at idle, all during driving and 30 to 40 mph up. Maybe someone else will chime in.
Does the ax noise at idle go with rpm? Or like a pulse that's ignition related? I had a plug wire shorting and it sounded super strange.
Ok so my experience with a bad torque converter felt more like the trans needed rebuilt in both cases. Half the reason I have a advance auto gm55 converter in mine is because I thought the trans needed rebuilt and the converter was a shot in the dark. Mine showed issues under lock up. It would have a vibration when it slipped under a light load on the 3/4 shift and locking up. But when I got on it on the highway it would free rev, or I could manipulate it to grab but it would always slip once power came in. My gmc 2500 would also vibrate under light loads like going up a hill.
Neither made any noises at idle, all during driving and 30 to 40 mph up. Maybe someone else will chime in.
Does the ax noise at idle go with rpm? Or like a pulse that's ignition related? I had a plug wire shorting and it sounded super strange.
Thanks for the input. Didn't mean to type "ax", meant to type "a". The feeling/noise goes away under power, I almost wonder if I'm being paranoid, and the fact that I have a good transmission mount, is transmitting vibrations that the old one couldn't since it was split. Between that, and the fact that the car was down for 8 months and maybe I forgot how it felt...I dunno. Been driving the car, and the converter/trans seems perfectly fine operationally, don't know what to make of it.
Ok, so I'm pretty sure i found the source of what I thought might be the converter/transmission. When I had the motor out a few weeks ago, I found the reason why the oil pan was wet with oil....had a pretty good gouge in it. I thought that the placement of the gouge was strange, but said eh whatever and just had it welded up. Well this morning I was crawling around under the car, and this here in the pic happened to catch my eye. I'm thinking that when I got the pan welded up...it then put the pan back in contact with the K member. Looks like I'll be jacking the motor and grinding the k member here soon.
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Strange vibration, torque converter?? 
