My truck recently started making a whirring noise coming from the transmission. It happens only when moving, in all gears and while coasting in neutral. It's usually loudest when cold. It sometimes audible when well warmed up after several miles of driving. The noise can be heard best from the shifter. The fluid level is correct. Is this a bushing issue or a bearing?

 

Remove the shifter boots so you can see the tranny and then listen.............

Does 4th have the least noise (direct drive, countershaft has no load)

 

The 4th gear check will be easiest. It has a console so taking it out will take some work.

 

I have the same issue with my 91 P/U M/T 4WD v6. Any luck on diagnosis?

 

I have the same issue with my 91 P/U M/T 4WD v6. Any luck on diagnosis?

 

Not yet. I've got a few other things to do today before I can check on my truck. Have you ruled anything out?

 

I had a whirring nose come from my pickup at the tranny while I was out during a 1k mile vacation. It was during any gear or neutral. It started out quiet and got louder until it was grinding. I found it was on the output or input shaft I don't really remember. I tore it apart to rebuild and all of the bearings were fried and the ones on the input and output shaft had an insane amount of slop. The previous owner did not take care of it before me. Rebuilt with japanese parts with a kit from ebay and its running perfect. I also have a whole another W56 of parts if you find need.

 

Also i'd start with tranny fluid levels first and then deduce where exactly its coming from.

 

agree with starting with the fluids. Drain it, check for high amounts of particulate in the fluid. Refill with a quality fluid and see if there's any change then go from there

 

The fluid level was fine when I checked it. It had a fluid change about 7K miles ago done by a shop the PO used. I'm wondering if they used the wrong fluid. Seemed thick enough when I checked it. I also keep wanting to think the shifter bushing is the cause. It has a bit of slop but doesn't affect shifting yet. I can hear the sound from the shifter itself. Sometimes it louder depending on the angle of the shifter.
The sound starts getting noticeable at just below 25 mph and the pitch goes up with speed. After several miles the sound can barely be heard.

 

The shifter bushing, I'm assuming you mean the bushing the shift ball sits in, should not be making a whirring sound unless my understanding of "whirring" is wrong haha. If that was the case, if you hold the shifter it should stop. Incorrect fluid, unless severely wrong, shouldn't cause it either. The trans taks a 75-90 GL4 fluid but I've seen people but anything around that viscosity in it (making sure it's GL4) without issue. I'm personal to redline MT90 but I've had super good luck with it.

Being that it sounds RPM dependent does it go away when you put the trans in neutral and coast at speed and come back when it put it back in gear? Have you checked all of your u-joints to make sure there's no play and everything has been greased recently?

 

Yes, I've checked the U-joints as well as the carrier support and all look OK. The support was actually replaced by a dealer a few years ago. It's actually had a lot of dealer service in the past.

 

That's good in regards of actually getting genuine Toyota parts if they're available but I have little trust for a lot of Toyota techs (really any mechanic) at this point.

Does the noise go away if you toss it in neutral and let it coast?

 

No, the noise is still there coasting in neutral. I live on a hill and I coast down most of 1-1/2 mile trip.

 

I think you said you tried some of these, but here are some other things you can try for diagnosis:
put it in neutral and shut the engine off, this will stop the input shaft from spinning and could point to an input shaft bearing issue. Be careful please.
lightly place your foot on the clutch, if the noise goes away this points to a throwout bearing issue.
put the t-case in 4x4 and see if it makes a difference
try T-case in neutral and engine off. once again be careful!!
disconnect the speedo cable and see if the noise goes away

as was already stated, if there is more noise in every gear but 4th it points to a bearing on the counter shaft, 4th gear is straight through with no load on the counter shaft.

Keep in mind that the driveshafts and shifter are like a telegraph, the noise could be from your differentials and it makes it sound like it's coming from your shifter.
you could also remove the rear driveshaft and drive in 4x4 to see if the noise changes.

without having my assometer in your truck it's hard to help diagnose a noise or vibration, help us help you and be as descriptive as possible, don't leave out anything that may be a clue!

 

All great ideas. I'll definitely be trying these things with the engine off. I'll have to see first how it behaves on level since there will be no power steering or brakes. The road I drive down is also a bit steep and winding.
I think the noise in the 4th is the same in 3rd and 5th. The pitch only changes with speed.
I didn't have a chance to spend time working on these things this weekend, hopefully next weekend.

 

I tried diving while coasting in neutral and with the engine shut off. Same noise. It may be the oil since the sound goes away after driving a few miles. It might get warmed up enough for the noise to go away.

 

the speedo cable is easy to eliminate, just unscrew the end at the transfer case.

 

Yes, I've looked the cable connection on the transmission. Just have to crawl under the next time and try it. The cable does make a sound every now and then but it sounds more like a rattling sound when it gets noisy. The noise comes from under the dash when I hear it.

 

I disconected the speedometer cable and there was no change in the noise. I also took the console out and removed the boot and drove around without a little. The whirring noise was much louder, sounded like it was coming out the rear of the transmission. I think the only thing left is to raise the rear off the ground, put it on stands and try running it to see exactly where the noise is coming from.