GTSSportCoupe
2LTE abuser
Mine has the exact same noise. 92 auto 1HDT.
Happens a couple seconds after startup.
Goes away with increased RPM
Quieter when in neutral or park
Sound is coming from inspection hole at bellhousing.
Not sure if someone mentioned this but very rarely the sound will completely disappear, but will quickly come back the next time I drive it.
I'm not sure if it was there before or after my full engine rebuild (7000kms old) but it is driving me nuts and I'm questioning whether the mechanic has stuffed up at some point.
If anyone has any information on this I'd be very grateful!
In your case it might be flex plate bolts. They need loctite or they can potentially come loose and become noisy as the plate moves back and forth against the torque converter. They can be checked through the inspection hole.