Read through quite a few threads, but I don’t think I am any more certain than I am unsure just exactly what the noise is.

I have a noise. It doesn’t sound like any bad belt or pulley I’ve heard before, so I’m kind of not thinking it is that. Plus, if it is a bad belt or pulley then I might feel some relief that it isn’t something more major.
It is a whining or whirring sound that seems to only be apparent around 30mph-50ish mph. Any faster (I’m diagnosing with the windows down) than that and I can’t really tell and any slower I don’t really hear it. It does sound like it is coming more from the front as opposed to the rear.

Observations:

• If I accelerate I hear it.
• If I am in neutral coasting I don’t hear it.
• If I am in neutral and I give it gas, I don’t hear it.
• I know I can hear it between 30-50mph, but any faster I couldn’t say. Any slower it isn’t noticeable.
• It seems to just mimic the RPMs, however only when in gear. As mentioned above it is not there if I am in neutral.
• If I am going 35mph and I manually shift it to 3rd the noise does increase hence the higher RPM (as mentioned above)
• It doesn’t seem to matter if the car is cold or at operating temp.
• It doesn’t seem to matter if it is warm or cold outside.
• It is not a squeal or screech, it is just a whine.

I’m inclined to think it is the gearbox and I may finally have to follow the write up on here and do the whole fluid flush and refill (I think it is 22in up on one side to drain and 22in on the other to fill….)
Although, could it be the transfer case?
I’m not really leaning towards the idea it would be the drive shaft bearing since I didn’t have any issue with any noise from the driveshaft before. Why all of a sudden?

However,…..
I did recently have the engine out to replace the cats. I think this is an important thing to note incase it points anyone in a direction that makes the source of this noise fairly obvious.
I feel I have ruled out drive axels, belts, pulleys and stuff since it doesn’t make the sound when I am in neutral. So it has to be something that is only engaged when in gear (like the gearbox, transfer case, driveshaft, etc…)

Prior to replacing the cats, I didn’t have any noises so I’m apprehensive to think it is the transfer case or driveshaft – but could be. You guys let me know your thoughts and I always appreciate the feedback. I’m not a professional diagnoser or mechanic. I just like to get my hands dirty working on the car and learn where I can, so I’m an intermediate novice (if that’s possible). This is out of my element though and I’d like to have some insight as to what it most likely could be so I’m not naïve when I take it down to the shop to have them check it out.

 

How soon was this noise noticeable after removing engine and refitting? If time has gone by from refitting the engine to when this noise was noticeable, did you have any issues separating the intermediate shaft ( in transfer case ) to the RH CV axle?

After refitting the engine, how did you refill the transmission fluid, you would've lost some when removing the engine

When you hear this noise, what happens if you put the windows up, can you still hear the whine noise? Is it only heard under acceleration, nothing on deceleration?

Transfer cases were notorious for whining, they would leak oil through the output shaft. They only hold about 600ml of fluid, so if any has been lost, either though leaking out the output shaft as many did, it could be this.

Do you have any friends who work at a repair shop with access to a hoist?

 

It's the carrier bearing

 

Thanks for the reply JB. Please see my answers below and some additional questions.

* How soon was this noise noticeable after removing engine and refitting? Right afterward. As soon as I picked it up from the shop I could hear it. I've only had it back for a week.
* Did you have any issues separating the intermediate shaft ( in transfer case ) to the RH CV axle? Although the noise was immediately noticeable, no. I am not aware of any issues and to my knowledge the CV axle(s) were not removed, just the engine carriage was dropped down.
* After refitting the engine, how did you refill the transmission fluid, you would've lost some when removing the engine? The shop invoice does not list any charge for transmission fluid, so I will assume there was no transmission fluid added.
* When you hear this noise, what happens if you put the windows up, can you still hear the whine noise? Yes. I can still hear it and it is rhythmic to the rpms. Sound aside, it reminds me of one of those wind up flashlights that you spin the handle to light it up.
* Is it only heard under acceleration, nothing on deceleration? It is heard under acceleration and deceleration. It is a consistent hum/whine/whirring that doesn't change pitch but does seems to increase in hum and decrease as the rpms go up and down when in gear.
* Transfer cases were notorious for whining, they would leak oil through the output shaft. They only hold about 600ml of fluid, so if any has been lost, either though leaking out the output shaft as many did, it could be this. I know of a write up to drain and fill the transmission fluid, but can the transfer case fluid be serviced?
* Do you have any friends who work at a repair shop with access to a hoist? I do not. I would have to take it to a shop. But, if I am on your wavelength, you are suggesting putting it in the air to isolate the noise? I am trying to figure out a way to do this. A last resort - so to speak - is putting it up on jack stands and hoping it doesn't fall off and go through my brothers garage. I figured I would start here in the forum so I had some ideas of what to be looking for.

It definitely sounds like it is coming from the front and not from the back. Still considering the TC or the Tranny as the issue, but with regard to the driveshaft.....Thanks again JB, and everyone that comments, for all the help!

 

Because he didn't properly mark the driveline flanges (as required in workshop manual or JTIS) before removing.

Your key component is "doesn’t make the sound when I am in neutral"

 

Correction/adjustment to this quote - It is a consistent whine/whirring sound that doesn't change pitch (as in it doesn't get more whiney or whistling) but does seems to increase in pitch and decrease as the rpms go up and down when in gear. Goes away when not in gear and the noise mimics the rpms when it shifts. I misspoke and said "hum" but I realized today that is just my tires on the road.

 

Interesting development.

I took it down to have it inspected and see if the noise could be isolated. The shop, different one than who did the cats (did this for an objective conclusion since they hadn’t done any work on it), checked the entire drivetrain and drove it on the freeway and in town for about a total of 30 miles. They concluded they could not find anything wrong and everything was in good shape. No leaks, sounds, carrier bearing was fine, driveshaft was in balance, etc... nothing seemed abnormal to them.

I decided that today, after much research on the forum, I’d try checking the transmission fluid because I thought it might be low. As I understand the level plug is maybe 6” to the right (drivers side - US) and maybe 1” higher than the drain plug. Here’s the interesting part - I opened the level plug and about a qt of ATF drained out. Having read it should drip out or else it’s overfilled I let it drain until it dripped. Put the plug back in and went for a drive. The tranny sounded absolutely terrible! All kinds of noises, wasn’t smooth to shift, literally felt like if I kept driving it would tear itself apart. I went back and put in a qt of Valvoline Max Life +200ml and it drives great! In fact, the noise I originally posted about is very subtle.

So now my question is, if there isn’t supposed to be more than what can just drip out of the level plug why did I experience this? Seems my car requires more than that in fluid. Also, what are the consequences or dangers of too much fluid in the tranny? I want to add more to see if the noise completely goes away but I’m apprehensive. Thoughts?