Schnit

86 toyota 4x4 truck auto trans. 198,000 miles all stock.

I haven't owned this truck more than about 1,000 miles and I'm not sure exactly what the problem is.

I get a mild roar out of the rear end with no vibrations at all...It's loudest around 50mph and is fairly quiet at 60mph. When at highway speed I coast but give it about 10% throttle I get a vibration and some louder roaring.

I jacked the rear end in the air today and brought it up to 60mph, vibration again at part throttle (pretty noisy, probably due to jackstands on the axles instead of tires on the ground).

With both wheels up there seems to be some play/slack when I take 1 wheel and turn it forwards/backwards. I do not get any play when I try to wiggle the wheels side/side/up/down.

I was under the truck a few weeks ago and in park I didn't feel any sort of play any direction that I wiggled/turned the drive shaft.

Thanks!

myyota

It sounds like you have a bearing going out in the rear axle, it could be an axle bearing or the pinion bearing. I had to replace the bearings in the rear axle on my 86 4Runner, and after 200.000 plus miles they were so loose that i could wiggle the bearings a 1/4'' in any direction. The new bearings made everything nice and tight again

Schnit

Are these bearings something a mechanically inclined person can do without special tools/training? I've done plenty of engine/transmission swaps, suspension and all that but never opened up anything.

myyota

The axle bearings are pressed on to the axle it self, so if you have a press then you should be able to do it. If not then you will need to take it some were and have it done. Don`t forget to replace the seals while your at it.

runner88

I had a very similar symptom when I first bought my 88 4runner. Definately a rumble and not a vibration.

I dropped out the driveshaft and it turned out to be the flange nut on the t-case. Tightened up to spec, about a 1/4 turn, and restaked the nut. Of course check the diff flange nut while you're down there.

Good luck!

1990yota-pickup

every thing will be listed in the fsm or hyanes manual

wilshire

This is probably your pinion bearing. The bearing preload may be too low. I'm not 100% sure but I think tightening the pinion nut, within specs, may help with that.

I had a very similar issue with my truck and I opted to swap in a used 3rd member. When I got the old one out, I could feel that the pinion bearing preload was very light. The new one went in and the noise was gone.

Schnit

UPDATE

Well I took some advice and did some seaching.

Dropped the driveshaft completely. The 30mm nuts on both the rear end and transfer case were finger loose. I tightened them to what I read on here in a few posts to 90ft/lbs, hopefully this does not create a worse bearing problem in the near future.

I also pulled the filler nut to the differential and found that it was nearly empty. I put about 1.5 quarts of fluid into it (all that I had in the garage) and called it good for now. Hopefully the fluid that was in there combined with the quart of valvoline 90wt combine with the .5 quart of royal purple doesnt cause problems LOL.

The roar/rumble is now completely gone as far as I can tell. I brought it up to 50mph and I noticed it was much quieter without any vibrations or noise at throttle, part throttle or coast....hopefully it stays this way =)

Note: I did not re-crush (or whatever it's called) the 30mm nuts. Hopefully this does not cause a problem either.

runner88

Great news. If you didnt restake the nut there's just a greater chance it'll loosen up in the future. A chisel or punch and hammer will take care of it. You could also use a few drops of locktite. But at least you'll know what it is if the rumble comes back !

Schnit

About 150 miles later and it's still much much better than it was before.

No vibration at coast or part throttle.

The only noise I hear is from the tires, exhaust leaks and the worn out weatherstripping

1990yota-pickup

u should have any issues with the oil. oil is oil...

its not like your cooking with it...

DavidMXRACER

I've had the same problem and I wish I would have read this posting on this subject. Mine finally came apart internally (w/lock right and 4.88's). I have yet to take apart once snow clears.