Humming from rear (1 Viewer)

[410225]

semlin,

i agree with ya. SO i called the dealer and talked to the mechanic who did the inspection. I am sorry to say this but what a door knob. He said main cause of the humming is the bearing in rear diff and it is the sign of wear over the time. He said he cannot guarantee it is that unless he take it apart and see it himself.
I told him, isn't that what initial check up should have been? What is my charge of $49.00 for? And why was he suggested replacing the whole third member instead of rebuilding or replacing just the worn part?
He said dealers are not to rebuild the diffs but rather replace. Also, $49.00 is a VISUAL inspection fee.
That just threw me off. I swear I am not going back to dealer for anything!

 

[cruiserdan]

There is a sort of easy way to take the rear diff out of the system for a "test":

This will require a CDL switch.

Remove the rear driveshaft.
Remove both rear axle shafts.
Drain the rear diff (to prevent gear oil from getting into the wheel bearings).
fashion covers for the exposed hubs.

Go for a drive.

This will take the rear diff completely out of the picture. Be sure to re-fill the gear oil after the test is completed or you WILL need a new one

D-

NOTE: If the vehicle has OEM diff locks, lock the rear diff BEFORE pulling the rh shaft. This will keep the dog clutch sleeve from falling out :whoops:

 

[Beowulf]

Adrian,
Just to calm any fears you may have, removing the rear axle shafts on a FF rear is a simple procedure. It sounds invasive but it really isn't. The only tough part is removing the cone washers and once you've done that a time or two it's also simple.

FWIW, I have not heard of an 80 series rear wheel bearing going bad but if one is bad then it is very difficult to tell where the humming is coming from. Someone could easily think the noise is coming from the diff. Removing the rear axle shafts gives you a chance to inspect those bearings and their lubrication. Don't be surprised when there is no grease and only diff oil. Several of us have had that experience. Get new OEM axle tube seals for the reassembly. They're cheap and the only seals you should ever use in your axles.

-B-

 

[semlin]

[quote author=MNCruiser link=board=2;threadid=6627;start=msg54980#msg54980 date=1067023931]
semlin,

He said main cause of the humming is the bearing in rear diff and it is the sign of wear over the time. He said he cannot guarantee it is that unless he take it apart and see it himself.

[/quote]

Adrian, so he thinks the "main" cause is the bearing, but maybe not after he opens it up? That advice and 50 cents is worth a 1/3 of a cup of coffee.

Sad to say you are learning the lesson that axles are better dealt with yourself unless you have lots of dough. If you hire someone else you will never quite know what they did and how many easy preventative maintenance steps they skipped.

I have finally admitted this to myself and feel much better. If you have a FSM and some free time I strongly urge you to follow Dan and B-Wulf's advice and DIY. If you plan to keep this truck, give in and learn about your axles. It will save you time, money and headaches in the future.

 

[410225]

Thanks for the great advise.
I am going to set this coming Saturday for myself to test and take a part my Axle shaft and rear diff.
I am going to follow Dan's test method and go by taking apart my diff.
I really appreciate all your help on this.

Adrian

 

[Rich]

Adrian, if you are going to the trouble of removing the rear driveshaft, then test drive it with driveshaft removed before pulling the rear axles. You have already reported that it does not hum when not under load. I'll bet with the rear driveshaft removed, it will not hum. If that is true, then there is nothing to learn by further testing with rear axles removed, other than how to remove and install rear axles!

If it does hum under load only, with rear driveshaft removed, then start looking at transfer case, transmission, and front shaft and axle. I don't think bad rear wheel bearings are going to cause a hum only under load.

If it doesn't hum with rear drive shaft removed, you still have not ruled out bad u-joints. However, the only problem I have ever had with u-joints was evidenced by knocking, not by a hum only under load.

Just in case you don't already know, if you drive the truck with one driveshaft removed, then you need to lock the center diff or you risk toastiing the viscous coupler. That's why CDAN said you need a CDF (center diff lock switch), the US 80s do not come with one installed from the factory.

Whenever I pull a driveshaft, I mark both ends of the assembly and the flange on axle and transfer case so I can install everything alinged exactly as came from factory. If the factory was so kind as to balance the driveshaft while installed on the truck than this will preserve the balance of the entire driveline. I do not know if Toyota was so kind.

Also, take time to apply grease to the splines before reinstalling. Good luck. You are bound to learn something.

Rich

 

[IdahoDoug]

Holy Cow. Adrian, I'm feeling like this thread is out of control a bit. No offense to anyone, but you opening up the wheel/hub, pulling the axles and then opening up the diff to inspect for wear on a Saturday is not realistic. Why? I've removed the rear axles and just doing that alone is gonna take most of a day before you open the diff if you also allow time to reassemble it. Not to mention you've got to have seals and gaskets on hand for reassembly that you're not going to find on a weekend.

Your post made it sound like we'd gotten you revved up that you could do this made me worried you were just going to put the truck on jacks and tear into it. (You didn't ask any details about what seals/gaskets you need, etc).

Having said all that, when you open the rear diff here's what you'll see: A bunch of oily gears. There won't be a bearing with a little note on it that says "Adrian, I'm the bad bearing that's just starting to whine a bit under load." I mean this as a jab at the guys here who are suggesting you'll be able to handle this, by the way - NOT at you. I want them to reconsider what they're recommending you do as I disagree with this course of action. Why? Detecting excess slack in a diff, improper wear patterns on the ring gear, or worn bearings takes serious experience. A normal bearing and a worn bearing will look identical to the naked eye until you strip things down and start using a micrometer on them.

Second, it's NOT a wheel bearing. Wheel bearings don't change sound when you're coasting. So get the notion that this will be a piece of cake and you'll open one wheel to find a note "I'm the bad bearing...." at the hub out of your mind.

If you're going to spend a Saturday doing something constructive, remove the rear drive shaft and by prior arrangement take it to a driveline mechanic for him to evaluate the condition of the rear joint. Or just have him do it on the truck. Or just have it replaced - they're not that expensive - though I'd have it evaluated first.

Unless there's evidence this truck was abused (You've still not mentioned its history), the statistical likelihood of a rear diff problem is extremely low at that mileage. I'd urge you not to get it into your head that you'll open the rear diff and be able to visually see the problem. First, rule out every cheaper possibility before you open that can of worms.

If there's a member in your area, ask if you can bring it to them next Saturday for a quick spin. Time much better spent than a misguided (in my opinion) belief you're gonna diagnose and repair a diff bearing on a Saturday afternoon. If that's even the noise you're hearing.

Take a deep breath here.

Doug

 

[410225]

Idaho,

Thanks for the reply. Honestly, I am a eager DIY person with very minimal knowledge on driveline. I am going by what others suggested and problem might be.
This vehicle was a one owner vehicle which was maintained by Toy dealer in Milwaukee. When I test drove, and bring it back from 300 miles away, I did not hear any humming or noise. It just happened recently while I was driving.
I have heard that it might be balancing the drive shaft issue instead of the rear diff. My question is when i remove rear drive shaft (I believe there are two, front and rear) and lock the center diff, is it okay to test drive 70mph? When I remove rear drive shaft, do I need to prepare for any gaskets for grease?
I did the tranny flush, diff oil is clean, grreased up the spiders and drive shafts, but have not done the tire rotation(another suggestion from member), and test drive without the rear drive shaft. I know I need to order gaskets for the rear diff if I decided to take it apart and you are right. I won't be able to tell what is worn and what is not. That's why I wanted to leave this to professional mechanic (Who told me it is the rear diff).
Thanks for your help.

 

[landtank]

How are the tires? I have had them slip belts before and give some humming noises. If the tires are old and near needing replacement you might consider that before tearing into the diffs.

 

[410225]

landtank,

tires are almost new. THat's why i was thinking maybe rotate the tires? But the hum comes from rear center of the vehicle only under the driving 65-70mph.

 

[IdahoDoug]

MN,

You mention the diff is full clean. I'm assuming this is the rear. How about the center diff?

Rotating the tires was mentioned to you a while back. If you've not done it, try that first - I assumed you had. While the tires are off, measure their circumference as precisely as possible and track where they were with marks. Then remove the shaft for complete inspection and balance by a pro. Be sure to mark it permanently - paint dots work well - to be sure it is put back on exactly as it was. No gaskets or oil on this - just a bolt on part.

Doug

 

[Beowulf]

Adrian,
C-Dan didn't suggest taking apart your rear diff. His suggestion was to eliminate the rear diff from the equation. He gave you a relatively simple way to do that.

Rich also gave you good advice to take a test drive following removal of the rear drive shaft. More ways to isolate the source of the humming.

I agree with Doug that you won't be able to tell much if you tear into the rear diff. I think Eric was suggesting that you can remove it yourself *after* you have determined that it is the source of the driveline noise.

Use a logical approach to isolate the source of the noise and then post back with your analysis.

-B-

 

[410225]

I am going to follow Cdan's suggestion. My question is, is it okay to remove rear driveshaft and drive 70mph? Won't it hurt the center or front diff?

 

[Beowulf]

Adrian,

>> Won't it hurt the center or front diff? <<

Do you have the switch on the dash that enables you to lock the Center Diff? It's commonly referred to as the CDL switch. If you do not have one then don't attempt this.

-B-

 

[410225]

Beowulf,

Yes. I do have one. I posted in another thread about engaging the CDL switch.
I will try this but have to wait. Business trip in the way before testing.
I will post back with the result.
Thank you all for your help!

 

[Zander8it]

Curious to know what you did and what happened. I myself, have a whole heap of issues too. 'Cept mine not only incudes the humming at around 65-75mph but the lovely "poop" grey-black color substance leaking out of my front drive-side wheel. What do you all have for this doosey?

By the way, I sold a Land Rover because I don't particularly care for leaking cars and this is 10x worse... Sorry, buyers remorse coming thru.

Any suggestions MN? Everybody? I'd be very curious to know what happened.

 

[PHAEDRUS]

zander,
look through the archives under birfield. in the tech section jim phillips has a great write up on change out and cleaning. your most likely culprit is the inner oil seal on the axle shaft. without any more info on your rig thats as far as I would go.
Dave

 

[410225]

Well, did the tire rotation, did the guys look at the drive shaft, no luck. Guys at the driveline shop is saying definately rear differential. They also caught front passenger side wheel bearing being really loose, which Toyota dealer did replace that wheel bearing. I am going to go off on dealer about the wheel bearing and going to have my guys rebuild my rear differential.

 

[Zander8it]

Dave-MN,
Thanks for the info. I will check into the Birfields section, although, as a LC novice, I doubt any DIY action will take place. MN, would a loose wheel bearing make that noise? Curious.

My rig: 94 with 96K. I bought it from a woman who apparently just drove it and not much else, but had some $ cuz she bought a new Range Rover. I essentially have no maintenence history at all, other than checking it over really well. Of course, the wheel leaking started a month after I bought it. The humming I never noticed driving it home after purchase, unless my giddiness blinded me from hearing it, although I doubt it.

Since they both happened at about the same time, wouldn't that lead one to think they are related?

What would a guy expect to pay for the service on the wheel portion should he decide not to bear the winter temps fixing it himself? Dealer? Private garage?

Any help, much appreciated.

 

[IdahoDoug]

$650 per side.