Drivetrain Noise (Video)

[PProph]

03 TB LTZ I6, 200,000 kms.

I tried a thread in the technical discussion but I've sinced narrowed it down to being something in my drivetrain, hopefully not in the transmission itself. Here is the noise I'm hearing (I was able to get good clear audio on it driving at night by some trees to echo the sound).

[video=youtube;HjyD6V0b4No]http://www.youtube.com/watch?v=HjyD6V0b4No&feature=youtu.be[/video]

The sound really kicks in after 5 seconds or so.
I've been trying to figure this for almost 2 weeks now.

More common when I accelerate, but not exclusive to acceleration.
More common at lower speeds, but audible sometimes at higher speed.
Coming from underneath, somewhere around the middle of the vehicle.
There is no play on the main rear driveshaft so I assume the rear diff and U-Joints to be fine, but I'm not a mechanic so I won't completely disagree if I'm told to check em again or a different way.
The front driveshaft has no horizontal or vertical play that I can notice, but when I spin it (disengaged) I am hearing what could be a similar noise where it connects into the transfer case. Or it could be a normal noise that is completely unrelated, I don't have enough experience in these matters.
I've read that a bad parking pawl can cause a ratcheting noise but I would presume that I would be noticing other problems (like park not working) if that were shot/going.
I do have a leaking front dif (I'm pretty sure), but the noise sounds like it's coming from further much further back than that.

The noise IS getting worse, and with winter approaching I'd like to knock this thing down sooner rather than later. I'm hoping it's just something I can fix rather than a larger transmission problem, but don't worry I don't shoot messengers.

Please help, you all haven't let me down yet! Please post me a solution or ideas or send me off to fetch data some way or another, I need some help to help myself!

 

[budro6968]

Could you make the video longer, in daylight? Is it happening at idle in park? While driving? What happens when rev's are increased. Put it up in the air and check in park. Have a friend you can trust sit inside and put it in drive while foot is on brake and lift brake pedal slightly and let the wheels rotate. You can speed up a little but keep slight pressure on brake pedal so you don't get a backlash. Make sure you brake hard, make sure the wheels stop before shifting back to park, or just turn off ignition to stop. When you jack up make sure you are using jack stands 4 to get it all in the air is best but if you only do the rear, block the front wheels. Do it on solid level ground. Be safe. Good luck.

 

[The_Roadie]

That's a concerning noise all right. Since the transfer case internals may be involved, does the nature of the noise change if you put it in A4WD or 4HI mode? (Don't run for more than a few hundred yards on dry pavement in 4HI)

What's the maintenance history? Have you changed the transmission fluid? At how many km? Have you been changing the transfer case fluid with GM Auto Trac II every 80K km?

 

[PProph]

@budro it does not happen while in park or in neutral. i had more videos in daylight and this and that but this was the best i could do for audio quality as it only happens while I'm driving and i can't recreate it in any specific way.

@roadie i'm probably not perfect on my fluid maintenance, however I bought the vehicle with 150,000k on it and at some point after that (say maybe 160 or so) I took it to a shop with a service 4wd light. they told me the last owner (who told me he had just changed all fluids) put the wrong type of fluid in the transfer case. they drained and refilled with proper fluid (i'm assuming the autotrac II you speak of).

i have switched into 4HI and noticed no major difference, I've done it a few times but since the noise isn't consistent it's very difficult to tell, but I'm pretty sure it has no effect either way (worse or better).

I'm still going to try and get it on a lift today or tomorrow (my gf's dad has one out of town about a half hour) so I can hopefully pinpoint the actual location of the noise. I only have 2 jackstands + one jack so I haven't really been able to do a stationary drive test.

also thank you for the replies so far. I will do my best to nab some more information today.

*i guess i'll add that I'm not entirely sure how the history was before this except to say that I'm not very trusting of the last owner's backyard mechanic. Between using the wrong transfer case fluid and his misdiagnosis of what turned out to be the faulty stepper motors (he thought the oil sending unit needed to be replaced, second gauge has since gone, I've got the new motors just need to get a hobby guy with a soldering iron to replace those) I'm not entirely certain of his competence.

I have had the Service 4wd light half a dozen times in the last year with what I assumed turned out to be the dial, as it always goes away and I get everything back when I shut off the vehicle and switch it back and forth a couple dozen times.

 

[PProph]

I didn't get a chance to do anything today, hardly left the house. Tomorrow I guess. I work nights and don't have a lit shop (was hoping to get it sorted out for this winter but i guess it'll have to wait another year but i digress).

Thought I would add that I have not had any problems driving. Don't feel any gear slippage or anything acting funny while I'm driving, it's all just the noise for now.

Also sometimes it will give me a loud "PING" when I put it into gear.

 

[gmcman]

That tinny noise would have me check the flex plate and torque converter bolts. Hopefully it's nothing in the transfer case but at least the flex plate is simple to check for either a crack or loose bolts. You will need to remove the access cover in the bottom front of the trans.

 

[CaptainXL]

Agreed. The noise is the same as if you rap on a flex plate with a bolt in open air. Would check it out as gmcman said.

 

[PProph]

Would I be correct in assuming that the access cover is the disc on the bellhousing that you pop out with a screwdriver? If so I believe I got a look in there and the flexplate looks fine however i was unable to spin it to get a look at everything. is there a better way to inspect it or at least a way to inspect more thoroughly? I just had it up on ramps for this.

I need to buy two more jackstands, been waiting to get it down to a hoist but it's just not happening. This is all becoming very discouraging.

I've got a short video that gives you the sound of the "PING" when I put into gear now (this is a more recent development, I'd say a sign of the problem escalating).

[video=youtube;GIPlZaaDGkY]http://www.youtube.com/watch?v=GIPlZaaDGkY&feature=youtu.be[/video]

One more note is a do actually have a little bit of play in the front driveshaft where it goes into the transfer case, but I'm thinking the problem I'm having just doesn't match up with that. Something I'll need to look at but not what's causing my noise.

And I checked my transmission fluid, but have not been able to get the vehicle up and level to check the transfer case fluid.

 

[gmcman]

I haven't removed the cover but it's the one with the two large rubber plug-looking things. The panel should come down, but someone else needs to chime in on it's removal. Not the round plugs, but the whole aluminum panel.

Once removed it will give you access to check all the bolts and any damage.

 

[PProph]

Finally got myself on stands to get it up and level. Good news so far, transfer case fluid level is good, color is fine (thank god it's blue I was a little concerned that yet another mechanic made a mistake). My u-joint at the rear dif is toast, so that's an easy enough fix sweet.

I know I need to replace the seals on my front dif, so hopefully this ujoint replacement clears up my noise.

Thanks for the help so far gents, I'll let you know how I make out!

 

[PProph]

Also from researching here I see that I might be getting the droning noise that one user said ended up being his pinion bearing caused by the faulty u joint? If so I guess I'll have to look at that too.

Recommendations on U-joints, greasable vs non? I'm not the most well known for doing things like greasing but I will do it if I have to.

 

[PProph]

I don't like to edit posts....

I've never changed a U-joint before but it looks pretty straightforward.

4 bolts from the rear axle to drop the shaft
It comes straight out from the transfer case at that point?

From reading on here looks like I'll need heat to get the old U joint off the shaft, is that correct?

Any special tools I'm gonna need? According to the book/manual I should be okay with the basic tools I have.

Should I change the rear dif fluid while I'm down there? It's not very pretty though the level's good. It's not black it's just kind of gunky and nasty smelling.

I'll be doing this on the weekend here. Gotta pick up the part (I wish rockauto shipping to canada was cheaper but I'll just buy local I guess) and then I'm good to go. If I need heat to get that joint off the shaft my brother's borrowing a basic torch from work.

Anything else?

 

[gmcman]

I would recommend a Spicer joint. You will need a press and yes, some heat. You need to melt the epoxy holding the factory joint. I would also change both.

 

[CaptainXL]

I wouldn't be heating anything. If you have never done it before you should get an alldatadiy subscription. Special tools are required for nylon injected joints.

 

[Harpo]

There is no need for any special tools.

I used propan torch and a socket to get mine out.

 

[CaptainXL]

There is no need for any special tools.

I used propan torch and a socket to get mine out.

You can rent the tool. Why waste propane and do it the wrong way?

 

[Harpo]

Because thats how you do it!!.

 

[CaptainXL]

Because thats how you do it!!.

Forget it. People don't do what he is doing. You will f up the driveshaft.

 

[PProph]

conflicting results!

Cap what does an altadata subscription provide me with besides what the haynes/downloaded manuals already have? It looks pretty straightforward to me. Also even the Haynes manual suggests it may be necessary to heat the u joint if it is the first time it's being changed, which I'm pretty sure it is based on the description I found in other threads (and my limited knowledge of the vehicle history before I bought it a couple years ago).

Also what special tool are you suggesting I require? Even the Haynes suggests the vice/socket method.

 

[Harpo]

Forget it. People don't do what he is doing. You will f up the driveshaft.

WHAT!!!!

You put a little heat on it and the plastic comes squirting out. Then tap the end cap in with a socket, no problems.

I have done it that way, have you,, ever??.

 

[Playsinsnow]

This is beyond my scope of DIY, but I believe my Haynes manual calls to use a torch. Small and low heat. You want to pop the PLASTIC, not alter the METAL. Right amount of heat should accomplish this fairly easy?

 

[The_Roadie]

The factory shop manual procedure uses a special tool in a press to shear the injected nylon retainer. In all my time on the forums, I've never once read about anybody buying this tool and using it. They always carefully use a torch.

 

[PProph]

Well I'm nothing if not careful. Not to mention methodical and deliberate (see *slow*) which is why it generally takes my twice as long to do a job as most people when it comes to diy. I guess being lazy adds to that time as well. In any case it will get done today. And now I have an excuse to buy a torch.

 

[budro6968]

conflicting results!

Cap what does an altadata subscription provide me with besides what the haynes/downloaded manuals already have? It looks pretty straightforward to me. Also even the Haynes manual suggests it may be necessary to heat the u joint if it is the first time it's being changed, which I'm pretty sure it is based on the description I found in other threads (and my limited knowledge of the vehicle history before I bought it a couple years ago).

Also what special tool are you suggesting I require? Even the Haynes suggests the vice/socket method.

GM has used the epoxy or plastic on their u-joints for many years. You have to melt it to get them apart. The small household type of propane torch will work but not as quick as oxy/acetylene. My XUV has an aluminum prop shaft and has the plastic to retain the u-joints. Basically don't over heat, Heat till it melts. If you don't have a good strong vise then use a heavy duty c-clamp and sockets. I did a roadside repair with the c- clamp method. Fortunately it was the rear joint very easy. I have seen guys use a big hammer with a ballpeen hammer to pound them apart, but I wouldn't do it like that. You might cause damage. It is not too hard just go at it and grease after you have the together. Have fun. Make sure to index the front joint before you take it apart since it is balanced in that position.

 

[PProph]

I plan to chalk positions on everything, quick question is what do I need to grease when it's together?

I'm also going to change my rear dif fluid at the same time.

I will be running out for some things (with another vehicle) right away and hitting this upon my return.

 

[budro6968]

I plan to chalk positions on everything, quick question is what do I need to grease when it's together?

I'm also going to change my rear dif fluid at the same time.

I will be running out for some things (with another vehicle) right away and hitting this upon my return.

Chalk will rub off, use a scratch awl or one of those engravers, even a screw driver.

 

[PProph]

*play by play update...

Got the driveshaft off, that puppy was on there. Gentle pry bar work (gentle/careful, it's all relative) got it off. One thing I notice is that there is a connecting little cross piece that was one piece with the snap rings for the two caps that go into the yoke (on the rear ujoint). this piece is broken, i believe it is to not allow those two caps to swivel independently. the new ujoint does not have this cross piece, just 4 snap rings. am i missing something or was this just a gm oem thing that matters not?

also when people say "larger socket head" they should point out that we're talking an inch and a quarter. I do not have such a socket head, going out to purchase one.

I've spent a lot of time buying tools (few related, i'm just a kid in a candy store when i'm justifying tool purchases) and installed my bench vise to my shop desk, i've probably only spent about half an hour on the vehicle itself lol.

 

[PProph]

Wow, that thing was in there. I couldn't get it myself, luckily I called a friend with a press and a better torch. Even with those tools it was fighting to come out, but we got it. All the pins had completely dropped out the one cap, I'm assuming that was my rattle that got progressively worse.

I put the new one in and finished changing the dif fluid (happy discovery that peavey mart sells amsoil and had the 75-90), I'm back on the road noise free! Thanks for all the replies and other info on gmt, this place continues to rock!

I'll be back when I have to do the front dif seals haha, that's likely in 2 weeks.

 

[HARDTRAILZ]

Forget it. People don't do what he is doing. You will f up the driveshaft.

Bullshit..I changed mine with a torch, socket, couple 2x4s, and a hammer and did not f up my driveshaft.