Trying to figure out what a server clunking/tapping sound is coming from my driveline, and have possibly narrowed it down to my very old NP 208 Transfer case. It happens with little load (cruising), and as soon as I downshift (and start engine braking) or upshift, (no load at all)? If I do not shift, it will contine until I slow down significanly. It will also go away if I apply throttle. It sounds like a loose converter bolt sorta, but Ive checked mine, and I dont think my flexplate is cracked, so I doubt that is it. Front inside the car it really sounds like its coming from the back of the drive train, not up by the motor. Seems to be most prevelent in drive, but thats the only time I really cruise at a steady throttle, and seems to go away when shifting into OD. And, it doesn't do it all the time. Sometimes its quite as can be.
I am getting a significant clunk while moving the tailshaft of the TC back and forth, even with the rig on the ground and the transmission in drive. Heres a video
Doesnt sound right to me, but my spare NP208 seems to do it too although not as bad (also, really old). Im running 400 ft lbs though this TC, and I have not regeared yet, and have a lower 1st gear (700R4) so Im applying a lot more torque then it is used to seeing. It did not do it after the fresh motor/trans install, but has progressively gotten worse, and is now really bad (only about 400 miles total). Ive only found 1 other video of someone spinning a NP208 and it didnt make any noise. Does this seem like it could me my problem, and if so, would a rebuild fix it do you think? Or should I look for a fresher TC?