KauaiRunner11

Hey guys, hoping to get some insight on this one. I have a 98 4runner, auto, 4wd, e-locker 224k pretty new to me. It's been making a kind of WHIRRING noise coming from the rear axle. Kind of hard to describe. I will attach a video to help more. The noise correlates to the vehicle speed, not rpms.
I replaced both wheel bearings, and axle seals (they were leaking) and it helped a little, but the noise was still there.
Checked driveshaft for play, none.
Decided to do the u-joints just to rule them out, no big deal right? A few u-joints in an afternoon, not too crazy? Well, got a crash course in Toyota double cardan joints, the hard way haha!
Anyways, DS is good, everything moves smooth, so ruled that out. Drove it with rear DS removed in 4wd, no noise. That rules out tranny/transfer case, no?
Is it possible for pinion bearings to be bad with no play in DS?
Any help is appreciated. I'm not afraid to tear into it, just don't have any experience with diffs aside from oil change. Thanks for reading.

wyoming9

iTrader: (1)

This is after ruling out road and tire noise .

Most times a whine is caused by how the Ring gear and Pinion mesh .

It can be from wear or a bearing starting to wear just enough to change how they mesh.

One of those things it might not get any worse for years or it can fail completely at any time .

If the gears are worn hard it is going to be time to replace no way till things come apart

ZUK

iTrader: (1)

With 224k, I am not surprised that it might very well be pinion bearings. You sure did everything else to eliminate the other variables.
ZUK

KauaiRunner11

Appreciate the replies guys, thanks.
Is it possible for the pinion bearings to be bad with no play at the DS?
There may have been a bit of denial that it was something in the diff that made me do all that, also I like to learn it all.

ZUK

iTrader: (1)

It's possible. If the history of those 224k miles is that the oil was neglected for
150,000 miles and it turned black then the outer pinion might start to moon crater.
The bearing becomes noisey. It can sound like a jet taking off when it really gets bad.

RustBucket

iTrader: (1)

Sounds very much like pinion bearings.

We were in Kaua'i earlier this year. What a fantastic place!

KauaiRunner11

Yea, been doing a bit more reading and that seems to be what might be causing it. I plan on removing the diff in the next week, then we will know for sure. Might just go ahead and get a master install kit, but we'll see. I will post some pics for posterity when I remove it. Let me know if you ever come back, I can give you the "toyota tour" haha.

RustBucket

iTrader: (1)

Sounds good! I'm sure I will at some point.

KauaiRunner11

Finally got the diff out, man was that a PITA! Anyways, just wanted to post a couple pictures and see what you guys think.

Co_94_PU

iTrader: (-1)

Pinion gear has some deformations on the coast side bevel. Ring gear surfaces look damaged, is that galling, if you can file a finger nail it's to rough.

KauaiRunner11

Thanks for the reply brother. The ring gear doesn't feel too rough, I couldn't file a nail on it at least. Would you say the gears are toast? I was going to replace just the bearings, but if the gears are shot I think I will try to find a whole 3rd to drop in.

Charchee

Just a thought. With the drive shaft removed and in 4WD, aren't all of the gears and bearings still doing their thing in the rear end while going down the road? Shouldn't you hear most of the same sounds coming from the rear end? I guess the pinion bearing might not howl as loud without the torque from the drive shaft but you should hear something if the bearing is starting to give up.

Again, just something to think about. I don't have a whole lot of experience with rear end issues other than with big trucks.

Co_94_PU

iTrader: (-1)

For the most part it's the same just less amplitude. Let off the gas at 20 and it's a cute little kitten snarl, let off at 60 and you start clenching holes in the seat with your buttock looking for a jumbo jet landing on top of you. So pulling the shaft is more of a sanity check, if it's quiet with one removed it's probably safe to say it's not the middle or other end.

Co_94_PU

iTrader: (-1)

Definitely wait for Zuk to have his say, but expect it's going to be something like "I need to see the pattern" if he doesn't spot something right off.

Excuse me while I ADD all over your thread.. Which makes me wonder if you can do an cheapo cheapy check with say Moly grease, cause I'm gonna be wondering about mine later if I manage to motivate and go pull it out.

PS: you checked for ply at the flanges after the shaft was removed, it will make it feel stiffer than it maybe.

KauaiRunner11

Definitely a good point. That would bring me back to the DS. I did replace the rear u-joint and the front u-joint of the double cardan. The double cardan didn't realy need to be touched, but I thought "what the hey, a couple more u-joints isn't so bad." Well after I destroyed the front u-joint getting it out I tried to put a new one in....wouldn't fit. They use a different size bearing that you can't even get from a stealership. So I stopped there. I was able to inspect the center ball of the double cardan and it was just fine, also the rear u-joint of the DC was smooth and free. Put it back in, regreased everything with the two different kinds of grease and still noise. Only thing I haven't checked is for a bent DS, but that would make vibration too, no? There isn't really any vibration, but yea, jet plane noise for sure. Thanks for chiming in.

KauaiRunner11

Hoping he can give some insight based on the pictures, probably better if I get some of that grease and repost them. Got a dial indicator yesterday to check backlash and runout, will post findings in a bit. Is there a cheapish tool for checking pinion bearing preload? I have an inch/lb torque wrench, but I don't think it goes low enough, and the beam style ones are a little out of the price range right now. I checked for play with DS installed. ADD all day long, don't bother me none. Especially if it helps us learn

Charchee

I kind of doubt its in your DS if the joints are new but if you find that yours is bad, I will have a spare in hand at the end of the week. I'm installing a locking diff rear axle from my parts truck and I'm going to use my spare shaft just because it doesn't have any rust on it. Mine is in great shape but has a little surface rust on it and I just don't like rust of any kind. Let me know if you need it.

KauaiRunner11

Wow! Thanks man, that's really nice of you. Here in the islands we embrace rust, haha. Just checking backlash and runout right now, numbers not so good. Will post findings in a sec.

KauaiRunner11

Backlash: .010
Ring gear runout: .004
Pinion flange: V-.003
H-.005-.006
Only thing in spec is the pinion vertical.
Also want to make note that there was resistance intermittently while spinning the diff. Felt like when there is crap a bearing.

Charchee

The noise you described sounds like a bearing noise to me and with that catch in it, you can just about bet on it. If it does have a little piece of debris in it, it's already done some damage to it so probably be best to go ahead and start replacing them while you have it apart.