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Discussion Starter #1 (Edited)
Recently I started to notice a whining sound from the front diff at 45 to 50 MPH speeds, only comes when slightly give it some gas and disappears when letting it off. ,, also disappears quickly after 50 MPH!

Any one faced this problem and got it fixed?


I hope its not a major problem in the diff that might require a rebuild or a whole axle change !

Tomorrow I'm planing to change the oil (just on time, around 17k miles from last change) ,, I'm thinking to open the front cover after draining the oil to look for any clues, .. I'm not experienced mechanically so I would like to get your advices about things to look for or test inside the diff to isolate the problem.

Current mileage : 65k miles
Quadra-Drive II
 

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Are you sure the sound is new Ahmed?...I know, weird question, but I always ask.
For example, " I never noticed it till I put tires on it " Meaning, the thing is so quiet now I hear a whine at speeds from 50 to 53 MPH.
It is not uncommon for a ring and pinion to have a slight harmonic at certain speeds.
If it was a bearing problem, I would expect it at all times while loaded or all times at coast.

Of course, I'm at a disadvantage at this distance, ha.
Regarding draining, obviously catch the oil but then, strain it through a cheesecloth....see what you get.
Very fine filings, like the metallic in paint is normal......fluid that looks like a metallic paint before you spray it is not normal.
But there will always be some metallic evidence of shearing......means nothing.

I won't recommend removing the cover unless the oil is looking like metallic paint......but at that point, you probably would remove the whole front diff for bench disassembly and diagnostics.

Rob
 

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As well, how do you know its the Front Diff and NOT the CV Joints in the driveshafts or even wheel bearings. I'd think the only thing to do at this point is to inspect and see if you can find anything wrong, and I wouldn't limit it to just the front diff, it could be wheel bearings or CV joints as well.
 

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With the exception of Robbie and a few others, I'm beginning to think you all are a bunch of poseurs. All I asked for was a little input, but no such luck. If I wanted to change my interior lights to neon, I probably would have received 100 replies!
Thats funny stuff right there :rofl::rofl::rofl::bowdown:
 

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Thats funny stuff right there :rofl::rofl::rofl::bowdown:
Pure Frustration - WWJD? :icon_cheers: Robby just about got it! :IThankYou:
 

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Discussion Starter #7
Are you sure the sound is new Ahmed?...I know, weird question, but I always ask.
For example, " I never noticed it till I put tires on it " Meaning, the thing is so quiet now I hear a whine at speeds from 50 to 53 MPH.
It is not uncommon for a ring and pinion to have a slight harmonic at certain speeds.
If it was a bearing problem, I would expect it at all times while loaded or all times at coast.

Of course, I'm at a disadvantage at this distance, ha.
Regarding draining, obviously catch the oil but then, strain it through a cheesecloth....see what you get.
Very fine filings, like the metallic in paint is normal......fluid that looks like a metallic paint before you spray it is not normal.
But there will always be some metallic evidence of shearing......means nothing.

I won't recommend removing the cover unless the oil is looking like metallic paint......but at that point, you probably would remove the whole front diff for bench disassembly and diagnostics.

Rob
I didn't add anything recently that would make the sound loader, same since several months.

I fact there was I bit whining sound when I bought it, but it was not load enough to consider it a problem, but the sound now is really not normal. and only appears on very limited speed range which as you said eliminates the the bearing issues and if I'm not mistaken its only the differential that make such sound!.

I didn't change the oil yet, planned during this week and I will try the cheesecloth method and see what I get. I will not open the cover thought as recommended.
 

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My guess would also be front diff. Possibly pinion bearing.
 

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Discussion Starter #10
The very first step in a whine diagnosis is to rotate the tires.

Certain tread designs can set up a harmonic as they trap and compress air between the small siping reliefs.

Obviously, you are verifying the sound has not changed in pitch or location.

Rob
That is not difficulty to test, but if the sound is coming from the tries then it would not disappear when I take off my foot from the gas at that the speed range, would it?
 

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Woops!

I forgot the 'only while throttle applied, not when coasting' part.

No, that removes the tire issue.....so, nevermind.

Back to the possibility of a pinion bearing.....power on noise= likely the bearing closest to the pinion gear or carrier bearing(s) Power off (coast)= usually the small pinion bearing closest to the seal.....usually the seal will begin to leak at the same time.

Trouble with noise diagnostics is, How does one determine what is abnormal?
If the whine is there at a specific speed as you say it is, but higher speed makes it disappear, I would be surprised if there was any bearing issue to be found.

Back to calling it a Harmonic or a Resonance.
Replacing bearings, resetting pinion depth and carrier pre load may make it disappear or happen at a different speed.

But again, volume has a lot to do with how to approach it.
If it's loud enouph for someone else riding with you to comment on it, without being provoked to listen for it, then it's loud enouph to be addressed.

As a aside, You mentioned having the mounts replaced once.....are you certain of their condition?
If any of the mounts are compromised, the normal gear noises will be amplified and will only be noted in a power on/or power off situation as the gearcase shifts around the mounts.

My thoughts,
Rob
 

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Discussion Starter #12
Back to the possibility of a pinion bearing.....power on noise= likely the bearing closest to the pinion gear or carrier bearing(s) Power off (coast)= usually the small pinion bearing closest to the seal......
Excuse my inexperience in this issue ,, here is a breakdown for the front diff ,, which part we are talking about?





.usually the seal will begin to leak at the same time.
Well as you mentioned the leaking issue, recently I noticed that there is little oil below the diff.. but not much to worry about.



Trouble with noise diagnostics is, How does one determine what is abnormal?
If the whine is there at a specific speed as you say it is, but higher speed makes it disappear, I would be surprised if there was any bearing issue to be found.

Back to calling it a Harmonic or a Resonance.
Replacing bearings, resetting pinion depth and carrier pre load may make it disappear or happen at a different speed.

But again, volume has a lot to do with how to approach it.
If it's loud enouph for someone else riding with you to comment on it, without being provoked to listen for it, then it's loud enouph to be addressed.
Till now no one noticed it and in fact only the wife riding the car since the sound was noticeable and she does not care about any sounds in the car (except the flowmaster muffler :))

The sound is also combined with a bit of vibration .. But I can assure you its not normal and wasn't there before and not in my first Commander.
 

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Hi Ahmed,
Just got back home.....car gang gathering every Saturday night....it is now 9:45 p.m. so, I apologize for not getting back to you right away.

The small gear that is part of the shaft is called the pinion. Item #'s four and eight are the pinion bearing and race sets.....inner is closest to the gear.

Item #13 is the ring gear carrier. The items numbered eleven (X2) are the carrier bearings.

Although pinion seals do fail, often, leakage at the seal accompanied by any abnormal sound is a sign of a bearing developing free play due to the case hardening flaking off the bearing rollers or race.
This, often is seen as a unusual amount of metal found while straining the drained oil.

I do think a close inspection of the case mounts is called for.
If they appear normal, block the wheels and put the transfer case in nuetral.
Loosen all the case mount bolts and push/pull on it.....it should wiggle about.
Then, re torque the bolts by gently tightening each till the case becomes tight, then finish tightening to specification.
This is a method used to relax the mounts and recenter the case within the frame.
I mention this only because the mounts have been changed once and the shop may have tightened one mount too much without allowing the gearcase to settle.

While there, verify the driveshaft to flange bolts are tight.....both ends.

Put the transfer case back in gear and go see if anything has changed.
If no changes, I guess you're about to learn about a gearcase repair.

Rob
 

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Discussion Starter #14 (Edited)
Thanks Robby for clarifying the diff parts.

So the oil should tell if there is bearing issue, hopefully tomorrow I will be able to change the oil.

Today I looked in the maintenance manual and found this which is relevant to the issue:

------- Quote from Maintenance manual ..

BEARING NOISE
The axle shaft, differential and pinion bearings can all produce noise when worn or damaged. Bearing noise can be either a whining, or a growling sound.

Pinion bearings have a constant-pitch noise. This noise changes only with vehicle speed. Pinion bearing noise will be higher pitched because it rotates at a faster rate. Drive the vehicle and load the differential. If bearing noise occurs, the rear pinion bearing is the source of the noise. If the bearing noise is heard during a coast, the front pinion bearing is the source.

Differential bearings
usually produce a low pitch noise. Differential bearing noise is similar to pinion bearing noise. The pitch of differential bearing noise is also constant and varies only with vehicle speed.

Axle shaft bearings produce noise and vibration when worn or damaged. The noise generally changes when the bearings are loaded. Road test the vehicle. Turn the vehicle sharply to the left and to the right. This will load the bearings and change the noise level. Where axle bearing damage is slight, the noise is usually not noticeable at speeds above 30 mph.



LOW SPEED KNOCK
Low speed knock is generally caused by a worn U-joint or by worn side-gear thrust washers. A worn pinion shaft bore will also cause low speed knock.

----------------- End of quote.


I think I'm having the first issue "Pinion Bearing" noise ,, and most probably the rear pinion bearing! which I believe part #4 in the diagram.

If that is the bearing which needs to changed, how big is this repair work? and will differential adjustment will be needed after that ? like the backlash and those things !! ,,, Or its only disassembling and then re-assembling after changing the bad bearing and seals?

Also I having that Low Speed Knock since I bought it, What are the U-joints?


Regarding the the diff case mounts, yes you are correct, the front diff mount and the upper diff bushing were replaced, the other bushing at the right side was ok at the time.

Loosing the front mount and right bushing seem to be easy ,, but I bit worried about the upper bushing due to the tight space and difficult access!!
 

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Case removal will be required for any repair.

Full disassembly is required and no one it their right mind would replace only one pinion bearing.....plan on both.

The carrier and ring gear are removed first......the bearing races and related shims must be kept in order of removal.

The pinion is removed from the case....as it is drawn out, the outer bearing (nearest the seal side) slides off the shaft.
The inner bearing must be pressed off the shaft and again, all related spacers are to be kept in order. The races require being driven out of the case.
Since the gears are being re-used, the odds are once assembled with the spacers as they were found, pinion depth, gear pattern, and backlash likely will be in spec with no additional spacers being required.

This is just a basic overview....I do not consider this a garage job for a novice.

Rob
 

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...This is just a basic overview....I do not consider this a garage job for a novice...
I have done some axle work, but never pulled a pinion.

I have read up on it, and have to agree with Robby, you need special tools to properly set the pinion depth, and you also have to be extraordinarily precise, setting bearing pre-load, etc. If you're NOT ultra-precise you can count on the differential at the very least making lots of noise, if NOT chewing itself up.

BTW, bearings and leaking seals, as I understand it, if the bearing goes bad, that part and the shaft that goes through the seal can wobble or go off center, this can damage the seal or at least stretch and deform the seal as it wobbles/goes off center and that opens a gap to let fluid past it, or can tear up the seal.

  • A minor leak, could just be a seal.
  • A major leak from a seemingly good seal, could be a bad bearing.
  • A major leak from a torn up seal, could be a torn up seal or a bad bearing.
  • If you replace the seal, properly, and the brand new seals leaks badly or gets torn up again right away, then it is very likely a bad bearing at the root of it.
 

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In the environment that Ahmed's in I'm surprised the bearing have last this long.

I just had my rear covered under warranty. Finally. 1 carrier bearing was scrap and the tech said he found an abnormal amount of sediment passed the pinion seal. I have know idea how that got there. In any event they replaced all bearings and seals.

Good luck with the repair.
 

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Thats true the mid-east deserts are murder on equipment, much worse than the deserts we have in North America. The sand has a much higher content of the harder and sharper quartz's and other minerals, as well, there is a lot more dust that works it way into everything.
 

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Discussion Starter #19
Ok ,, today I replaced the diff oil .. it looked burned.

I managed to capture some amount of the front diff oil in a bottle and passed about quarter of liter through cheesecloth .. here is some pics .. I don't see any metal particles.








against flashlight ...










Also I took a photo for the rear end where it meet the drive shaft ,, there is not any oil leaking from there

 

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It may be the light or photography, BUT, it looks like there is a lot of dirt in the oil to me.

Maybe get some cheap axle oil and try to flush out the diff case some? Then fill it up with the good stuff?

Lets keep our fingers crossed, maybe the dirt in the oil caused the noise and fresh oil will fix the problem.
 
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