Weird drivetrain noise

First a little background: '55 CJ5, Chevy 283, SM465, AA kit to Dana 18, Warn OD. I got up and drove the Jeep to town this morning. It's about 6 miles on the expressway at about 65mph, nothing I haven't done before. I was decellerating off my exit and was nearly stopped when I heard this funky squeal/whistle noise coming from the tranny/tcase. I took off from the stop and the noise wasn't there. Next time I decellerated it came back. (If you've ever heard a high speed shaft spinning in a sloppy dry bushing that makes that chirping squeel noise, this sounds very similar). It's never done this before. I got what I needed from the store and took the back roads home. By the time I got home, the noise was there all the time. It's very consistent when accelerating or under constant load. When I decellerate, the noise seems to speed up slightly at first, then slow down. It's also inconsistent when decellerating, it comes and goes and changes speed. Put my foot back on the gas, it comes right back. With the tranny in neutral and the Tcase in gear it seems to be road speed sensitive. With the tranny in gear and the Tcase in neutral, it's engine speed sensitive. The OD seems to have little effect on it. Any ideas at all??? I really don't know where to start except to check all my fluid levels and look for metal..... I really don't want to just start taking everything apart until I find the problem. Thanks in advance :?

 

Does the sound go away when you push in the clutch?

 

x2 (throw out bearing? )

 

X3....tob

 

:iagree: :iagree: 9 times out of 10 with that kinda noise.

 

Noise doesn't go away when I push in the clutch....

With the tranny in neutral and the Tcase in gear it seems to be road speed sensitive. With the tranny in gear and the Tcase in neutral, it's engine speed sensitive.
That pretty much eliminates the tob...

 

I 've had my pilot bushing make that kind of noise before. Although it should go away when the clutch pedal is depressed. It wouldn't make the noise when driving either. Just as the pedal was being pushed in. Wish i had more to offer. Damn! I hate mystery noises!

 

Pretty much gotta be somewhere in the transmission with what you have said here. I would check the tob just to make sure because you are gonna have to drop the tranny anyway. Could be the output shaft bearing or something else internal. I would just have to drive it to be able to make a decision.

 

I'm going to have to argee with the rest, it is a throw out bearing. That funky squeal sound, sounds like a THB going dry. If a TOB is not adjusted right and turns all the time it will go dry, they are designed to turn only when you push in on the clutch. Transmission sounds or bad bearings going bad are in oil, so they don't produce that dry squealing sound, but a TOB is pre-packed with grease and when it is run dry will produce the dru sqealing sound. Like the previous poster said, start there first, because you are going to have to pull the trans anyway. I maybe wrong, but I don't think so.

 

Kinda why I am still thinkin tob. Never can tell unless I drive it.

 

Basically, you learn from your experiences. Just strip the whole Jeep down to the frame and rebuild it. You will feel better.

 

Alrighty, here's the update. The first thing I checked was my gear oil levels in the tranny and tcase. They were both full, but when some of the oil ran out I noticed it was EXTREMELY thin....like hot 5W30 thin... That can't be good so I drained and refilled both cases. I figured I try driving it to see if it had any effect on the noise. I pulled out of the driveway and the noise was gone... So then I proceeded to flog the everliving s___ out of it for a half hour just to see what happens...still no noise. Sooooo, the fluid change seems to have made it go away. I did check the tob adjustment and it's fine. It doesn't contact the clutch fingers unless the pedal is depressed. I guess I'll just keep driving it and see what it does. Thanks for the advice

 

Been there, done that, lol

 

That would do it once it gets hot. That is why I said I would just have to drive it to be able to tell for sure. A tob has a definate sound when it starts going bad. I didn't think there was much chance of you stoppin by here in it so I could listen to what it was doing though.

 

Sounds like a rev it till it goes or blows thing.

 

Not necessarily what I would recomend to someone, but its what I always do.

 

Noise come, noise go.
Myself I've never done that. Yea right. R) Had a sand rail that I blew the pressure plate apart on at around 7k rpm. Never made a sound till it went.

 

I've never been that lucky either. If mine starts making an unusual sound, something bad has happened. Usually in the rear end. I have never found a rear end that I can't break with just my foot. Like the Jeep I have for my daily driver. Got a D44 rear and only running 30 x 9.50 street tires, but I am on my third ring and pinion set.

 

I blew up a D60 once. R)