Weird noises under truck

Irbullet · June 18, 2018

Well, 2 days ago I bought a 05 Silverado z71 stepside, and I notice what sounds like rocks going around under my truck? I don’t have any vibrations or any other odd things going on, just the noise. It happens whether I’m in N or D when rolling. It sounds IDENTICAL to this video:

does anyone have any ideas on what it is? I’d assume driveshaft, but does that mean replacement or what? I’m new to these trucks, and I’d appreciate any sort of help.

thank you!

Supreme Pizza · June 18, 2018

Sounds like a piece of metal or something rattling around inside the drive shaft. Unbolt the rear of the shaft, hold it lower than the front of that shaft, and shake it up and down. Might be worth a shot.

Irbullet · June 19, 2018

5 hours ago, starman8tdc said:

Sounds like a piece of metal or something rattling around inside the drive shaft. Unbolt the rear of the shaft, hold it lower than the front of that shaft, and shake it up and down. Might be worth a shot.

This is what I will try to do. I am going to take front and rear drive shafts out and replace the u joints while I am at it, and apply grease as needed. I’ll update if this fixes the issue or not.

thank you

Supreme Pizza · June 19, 2018

You probably already know this, but make sure you don't mix grease types. The grease in the bearing from the factory may differ from the type you are going to add. If they are not compatible, the grease will turn to a liquid similar to pen ink, or it can turn hard and chalky. Either way, it destroys your bearings. You must clean the old grease out completely, with paper towels, Q-tips, and brake cleaner. Then you can apply new grease.

Irbullet · June 21, 2018

On 6/19/2018 at 8:28 AM, starman8tdc said:

You probably already know this, but make sure you don't mix grease types. The grease in the bearing from the factory may differ from the type you are going to add. If they are not compatible, the grease will turn to a liquid similar to pen ink, or it can turn hard and chalky. Either way, it destroys your bearings. You must clean the old grease out completely, with paper towels, Q-tips, and brake cleaner. Then you can apply new grease.

Damn. Didn’t fix anything. Also 4wd sounds like it’s going nuts almost like birds are chirping / sounds like a slight grinding noise. I’d assume the noise is related to the 4wd issue. I have autotrack transfer case. I just bought this truck. Yay. Any ideas?

Supreme Pizza · June 21, 2018

This might be of some use:

https://www.amazon.com/Powerbuilt-640582-Mechanics-Stethoscope/dp/B004KEHGZY/ref=sr_1_11?ie=UTF8&qid=1529582436&sr=8-11&keywords=stethoscope+mechanics

Supreme Pizza · June 21, 2018

Prior to replacing parts, you may be able to identify the issue by testing the parts separately. For instance, you could remove the drive shaft, and put it in gear. If the noise is still there, then you know the drive shaft and axles are not the issue. If the noise doesn't go away when you remove the shaft, then you know its either the rear end or, the brakes, or the driveshaft itself. I have seen posts where people were developing holes in the T-case, caused by internal parts rubbing on the case. Might be a bad bearing somewhere.

Obviously who ever sold the truck, did so due to mechanical issues. No one ever sells a vehicle because it was too reliable. I usually spend about an hour looking over and testing a vehicle before I buy it. Every little thing I find causes the price to go down even further. If I find any major issues, I either get the rig super cheap, or I pass on it all together.

Irbullet · June 21, 2018

8 hours ago, starman8tdc said:

Prior to replacing parts, you may be able to identify the issue by testing the parts separately. For instance, you could remove the drive shaft, and put it in gear. If the noise is still there, then you know the drive shaft and axles are not the issue. If the noise doesn't go away when you remove the shaft, then you know its either the rear end or, the brakes, or the driveshaft itself. I have seen posts where people were developing holes in the T-case, caused by internal parts rubbing on the case. Might be a bad bearing somewhere.

Obviously who ever sold the truck, did so due to mechanical issues. No one ever sells a vehicle because it was too reliable. I usually spend about an hour looking over and testing a vehicle before I buy it. Every little thing I find causes the price to go down even further. If I find any major issues, I either get the rig super cheap, or I pass on it all together.

Well, the good news is I have a donor vehicle with same type of transfer case (which I know has no issues) and other 4wd parts / drivetrain parts. I just need to figure out what I need to switch around.

im gonna do more testing on each part as you stated, I will post about what I find as I couldn’t find a “solution” to this problem.

also, could these cv joints be causing issue? Both sides have similar play. I’m not sure if this is too much play or not. I cannot find play / recreate noise in any other suspension or drivetrain parts.

I really appreciate your time. I’ve spent way too much time working on a new to me vehicle, lol.

Supreme Pizza · June 21, 2018

To eliminate the CV axles, front drive shaft, and front differential, you could either remove the front drive shaft during the test, or just leave the truck in 2x4 mode, and only raise the rear end.

Are you sure there is not a piece of metal bouncing around inside your driveshaft? Like inside the center of the hollow driveshaft tube.

As you can see, they are hollow:

Irbullet · June 22, 2018

2 hours ago, starman8tdc said:

To eliminate the CV axles, front drive shaft, and front differential, you could either remove the front drive shaft during the test, or just leave the truck in 2x4 mode, and only raise the rear end.

Are you sure there is not a piece of metal bouncing around inside your driveshaft? Like inside the center of the hollow driveshaft tube.

As you can see, they are hollow:

Yes I shook the hell out of the driveshaft, lol. Didn’t hear anything.

and yes it still makes noise with front driveshaft removed.

Im honestly about to break down and take it to a shop. Would rather not though!

Dnt · June 22, 2018

My first guess would have been a dry/bad u joint but you said that you replaced them? so my next best guess would be a microfracture in the driveshaft tube. Give it a good steel wool cleaning and look for a crack. i noticed on this 2018 6.2 that they have beefed up the driveshaft........................

Irbullet · June 22, 2018

Will a driveshaft off a 2001 suburban (4x4) fit my 05 ext cab z71? I can try switching that out to just eliminate driveshaft as the culprit.

that is my donor vehicle

I’ve never had such a hard time fixing an issue on a car before!

Supreme Pizza · June 22, 2018

Don't take it to the shop. I will not give up, if you don't. I suggest removing the rear drive shaft, and then put the trans in gear, while in 2x4 mode. That will determine if the noise is coming from the transfer case or rear end.

Supreme Pizza · June 22, 2018

This could be something stupid, like a rock inside of a rim.

One specific part is causing the sound, you can track it down. Process of elimination. Eliminate the wheels as a cause, eliminate the rear axle, eliminate the drive shaft, eliminate the transfer case, and so on.

Irbullet · June 22, 2018

1 hour ago, starman8tdc said:

This could be something stupid, like a rock inside of a rim.

One specific part is causing the sound, you can track it down. Process of elimination. Eliminate the wheels as a cause, eliminate the rear axle, eliminate the drive shaft, eliminate the transfer case, and so on.

I will get it up in the air again tomorrow and post my findings. I’m going to restart the elimination process to see if I missed anything. Whatever this is, I will post the solution once It is found.

I really appreciate everyone’s time on here. It’s very helpful.

Meanwhile, here’s a photo of my new to me (but broken sounding) truck!