Troubling drive-train noise - need help to diagnose

[whitetoy]

          Truck specs :
1984 4Runner
G52 tranny (original, never worked on)
    switched tranny oil to Redline GL4 in January to smooth-out shifting,
    and help out tired synchros.
Marlin gears in single case with twin-stick conversion
Front wheel bearings  are less than 1 year old.
Right rear wheel bearing about 2 months old.
Left rear wheel bearing might be original, does not get hot
4.88 gears, with detroit in rear (set up by Gearman).

The noise sounds like a bearing going out, but I'm no expert.
Doesn't matter what gear I'm in.
Doesn't matter if clutch is in or out.
Not very loud, can't hear it with stereo on.
Not the motor, since the noise occurs even with motor off, coasting.
No noise when cold, noise starts after maybe 15 or 20 minutes.
At first, the noise didn't start until about 20mph.
Now, the noise occurs at about 15mph (getting worse?).

Can't really tell where it is coming from, since I only hear it when moving.
The noise seemed to start shortly after I put in the Redline gear oil last January (related?) .
Truck runs great otherwise.  Shifts fine.

Any idea what this might be? Is this typical of a tranny bearing going out ?
How can I narrow it down?

Thanx for any help.

[MiniSimp]

Is it a squeak, squeak, squeak?
Or a continous noise?
Any metal on metal sound?

[Skinny_Pedal]

are you sure its the tranny? have you checked your u-joints. there tedious little turds

[oddball]

describe the noise , wheel bearings don't all make the same noise when they are bad at least from my experience

[whitetoy]

describe the noise , wheel bearings don't all make the same noise when they are bad at least from my experience

Its not a 'squeak-squeak', but a continous, fairly high-pitched, whine.
the noise doesn't seem to change (frequency or loudness) with speed.
I'll try removing my rear-driveshaft this weekend, and see if that makes it
go away.  It would be nice if it was my u-joints, and not my tranny.
U-joints are only a couple of years old.

[reklund5]

Sounds like th input bearing on the tranny to me.  Try switching back to regular 75/90 gear oil and see what happens.

Ryan

[brainlessfool]

do you have a drive shaft bearing? of so mite want to look at it to. 

[yotaboy79]

does it do it while coasting with the clutch in and tranny in nutral if it keeps making noise then its not the input could be out put or t-case in put or out put drain your tranny and t-case oil and check for metal shavings or in my case ball bearings and gear teath

[germ]

Me thinks you should check your brakes as well.

Erik

[blackdiamond]

When my first universal joint failed it sounded like a coat hanger wrapped around the driveshaft, the second one I don't remember the sound it made but I noticed the slop in the drivetrain, it was shot!  The gease line got plugged to two of the four bearings and they turned to powder.

Do it change under deceleration at all?

[Duffil]

id say tranny brg...mine is hosed and it does that...kinda almost sounds like a turbo...

[Marlin]

Drive your truck, and take special care as you drive in 3rd, 4th, and 5th.
If you hear the noise in 3rd, and it gets quieter in 4th, and then loud again in 5th, it could be in the trans.
No change noted, check motor mounts, center pins and u-bolts.....

[whitetoy]

Thanx for all of your replies.
This evening, I  removed the rear drive-shaft, locked the hubs and went for a drive.
NO NOISE !!!   
The u-joints are fairly new, so I'm shocked that was it. (not Toyota brand, however).
I am now assuming that it is the front u-joint.  I've always had difficulty lubing it, because of the front-facing location
of the zerk and no room around it.  Just can't seem to 'snap' the grease-gun fitting onto it enough to seal around the zerk.
The u-joint is likely just dry, and I can't get grease into the 4 'corners'.
Can I get a narrower grease-gun tip so it will fit in there? Otherwise, I'll  have to get it replaced again.'

[brainlessfool]

you can get a "pencil tip" for your grease gun.

[whitetoy]

Thanx, I'll look for one tomorrow.
BTW, anyone know if the  driveshafts are the same as on the 2wd trucks ?
More plentiful in the PNPs.

[brainlessfool]

no I think the 4X4's are shorter.

[Uncle Jesse]

as far as the actual driveshaft tube, I don't know if they are the same.  As for the whole driveshaft assembly, the 2wd has a slip yoke on the trans end, and the 4wd has a flange on the trans end. 

If you have to replace your u joint, I believe they make joints that have the grease zerk on the cap, instead of the body of the joint, making it easier to grease.