Front differential hum - not wheel bearing? - video included

[Sheehanigans]

Hey all,

I have a 2006 Envoy at 130k, with the 2HI,AUTO,4HI,4LO transfer case. 99% of the time it stays in 2HI as recommended.

Anyways, after a 900 mile road trip in two days I noticed a hum coming from the front end on a smooth road. Louder on a right turn, quieter on a left turn made me think driver side wheel bearing - no problemo. Ordered the timken and went to install it today, but now it's something worse.

The hubs are solid, no play or grinding. The noise is coming from the front differential case. It's a low clicking noise, like straight cut gear teeth contacting each other with no oil. I drained it and it looked like it had enough, at least 0.5 liter by guess (manual calls for 0.8?). And it was smooth black, no grey milk color to it, no noticeable shavings or metal particles.

Filled with synthetic 75-90, still heard the noise turning by hand, but went for a drive around the block anyways - still there.

There is maybe 1mm of linear movement in the drive shafts, same on both sides, and there is no noise when turning the passenger side wheel. It turns a little easier, if that means anything. There is a some play in the CV joint on the driver side, and a little less on the passenger side, but still there.

Here is a video of it. The noise seems to follow the speed of the gear that you can see in the video, closest to the oil pan, and is turning the opposite direction that I am spinning the hub. Noise is the same when spinning reverse or forward.

It is quiet below 35, then above that on a smooth road it is certainly noticeable in the cabin.

Any ideas?

The video makes the noise seem louder than it really is, but you get the idea.
https://youtu.be/MjyUlT_7DMc

Also, I found this video of another person hunting the noise. Both inner CV joints (the two closest to engine, driver and passenger shafts) have a similar slop to them, but not quite this much:
https://youtu.be/pRMtuU36lsI

 

[gmcman]

Louder noise when turning left would point to the passenger side wheel bearing, that's the side being loaded up when turning left.
Does it sound like a mud tire when driving? That's what the hub and bearing sound like when failing, good rule of thumb is to replace both at the same time.

 

[Wooluf1952]

Welcome

In case you haven't heard:
http://gmtnation.com/forums/topic/218-welcome-to-gmtnationcom-heres-the-story/

The OP said it was louder on a right turn, which often means a bad or going bad left (drivers side) wheel bearing. However, we have seen that isn't always the case.

 

[Mooseman]

I've heard that noise before but can't remember where from but it was probably a differential. Is the noise coming directly from inside the differential or is it possibly coming from the other side in the disconnect? Try putting it in 4hi (not a4wd), shut it off and try again. When you turn the wheel on one side, the other should turn in the opposite direction. If no noise, I'm thinking a disconnect that isn't fully disengaging.

 

[Sheehanigans]

The noise in my video (the first link) definitely comes from the drivers side of the differential. I can put my finger on the case and when I spin the hub, I can feel a vibration in the carrier case for every tick of noise. Spinning the passenger wheel makes no such noise. Basically you can feel that noise in the video on the diff case.

I cycled through the transfer case positions today, and the noise was still there on a test drive.

Basically, is this ticking noise normal when spinning the driver side wheel? I didn't install the hub/bearing today because I wanted to research more. If this noise is normal I'll go ahead and do the hub but I didn't want to throw money at one thing if there is another thing worse on the other end of the shaft.

I really appreciate the welcoming and help!

 

[gmcman]

The OP said it was louder on a right turn, which often means a bad or going bad left (drivers side) wheel bearing. However, we have seen that isn't always the case.

Yes he did, my bad...my eyes picked up the next line.

Man, I watched the video and that sounds pretty bad. Anyway you can get an inspection camera in there to look at the spider teeth?

 

[Sheehanigans]

Yeah the noise is quite amplified on the mic - it's a little more subtle than the video portrays.

I was just thinking about that camera idea.

Does the play on the CV coupler (the rusty bit next to the CV? does it have a better name?) indicate a bad bearing on the side of the differential? And maybe that is causing the pinion gear to misalign with the ring gear? I've done traditional 4x4 gears on solid axles before, not sure what to call the parts on this front 4WD setup. The ticking directly follows the speed of the teeth in the video, so they must be out of mesh somewhere...

 

[Mooseman]

The differential should be absolutely silent. Yours is not. An inspection camera would help. There have been reported failures of front diffs. Usually it's replaced with a used yard unit. If you have to, you could remove the axles and drive shaft and plug the holes with Gatorade bottle tops and tape until you replace it. And apparently it's a tight squeeze to get it out. Manual calls for the removal of the oil pan but have heard of some possibly pulling it through the top. I would rather go without 4x4 than remove the oil pan again.

I don't think it's worth it to try and fix it. There is some level of complexity with this design.

And yes, you can drive it like that without the axles. The hubs are designed for it.

 

[Sheehanigans]

[SIZE=medium]It looks like I can get a used differential assembly for about $400. I called around and got time estimates of 11-12 hours for any kind of differential work on this car. Yikes. [/SIZE]
[SIZE=medium]Is this a reasonable procedure to tackle myself? I have no engine hoist if it needs to be pulled, but can do tie rods and suspension work without a lot of trouble. Can it be done in 20 hours DIY? Any really special tools or techniques?[/SIZE]
[SIZE=medium]I figure there are two options - $500 for the DIY used assembly and misc stuff. Or buy nothing and tear out the axles to make this a 2WD vehicle. I plan on keeping this car for another 5 years if I can avoid problems like this one. With 15 years and 180k miles, I’d be happy with scrap metal value at that point. [/SIZE]
[SIZE=medium] [/SIZE]
[SIZE=medium]Just to confirm, since I have heard conflicting answers, this vehicle can be driven with no spindle of any kind in the front hubs? No need for axle stubs there? No dust and moisture guard anywhere?[/SIZE]
[SIZE=medium] [/SIZE]
[SIZE=medium]And the CV tripod end will hold itself in the differential without an axle? Definitely won’t fall out with the miles? I’d like to have the option to repair this and get new axles.[/SIZE]

 

[Mooseman]

I would believe the time estimates because of the tight fit and work involved. Reading this write up at ORTB, it seems doable but is a lot of work.
http://www.forums.offroadtb.com/viewtopic.php?f=72&t=1351&start=40#p30255

And this one:
http://forums.offroadtb.com/viewtopic.php?f=72&t=5849

And yes, you can drive it without anything in the hubs. Only the TB SS needs stubs. The ONLY exception is one particular brand of hubs (maybe Detroit Axle but I'm not sure) that specifically say you can't. Timken and OEM are OK.

And the tri-pots will hold in the diff. You will have to remove the driveshaft to keep the front diff from possibly spinning.

 

[Texan]

I am biased against FWD vehicles, but family members in the past
had FWD GM,s. That noise reminds me of a worn out constant
velocity joint on the axle. I would suggest pulling that axle and driving
around the block, as a test.