2008 Tahoe LTZ. No oil. Added 2 quarts, dipstick still doesn't show anything.

[George B]

Would this cause a clunk, even if it isn't in 4wd?

As far as the diff. Yeah, both have play. Should the bolts that touch the axle have a bushing? Or can I just tighten them?

You can just tighten them.

 

[Dustin Jackson]

@User_Name I don't know if the front diff being loose would be the cause of your problem, it certainly should be addressed tho.

For fun.. pop the hood, start the tahoe, and put it in drive. Hold the brake pedal down while you give it throttle and try to do a little burnout and watch your motor while you listen for the clunk. If the motor lifts and clunks you'll have found your problem.

 

[OR VietVet]

Address the obvious first: U-joints, loose bolts and if you find motor mount play-replace them.

 

[swathdiver]

It's hard to hold the phone and push the hog up with one hand, but this is just to give you an idea how much play there is. With two hands, it doubles.

Would this cause a clunk, even if it isn't in 4wd?

As far as the diff. Yeah, both have play. Should the bolts that touch the axle have a bushing? Or can I just tighten them?

The differential housing is secured to those brackets by 2 bolts on one side and 2 nuts on the other side. Try tightening them first or just reach up there and see if they flop around. Some movement is normal. The OE U-Joints are solid and not greaseable. In my opinion, solid is stronger and better than a greaesable u-joint.

Bracket, Front Differential Housing, Left 23104736
Bracket, Front Differential Housing, Right 23104735

Front Drive Shaft U-Joint 1344 23104840
Rear Drive Shaft U-Joint 1350 89059111

 

[Doubeleive]

It's hard to hold the phone and push the hog up with one hand, but this is just to give you an idea how much play there is. With two hands, it doubles.

I suspected my clunk was coming from the same place because everything else was good at the time so I bought new ones and had them installed, they gave me the old ones and sure enough the rubber was shot it would just crumble in my hand like it was a 100years old, I think you probably need multiple things replaced including new u-joints and probably motor mounts as they go out just as well, when one thing goes it puts wear on the rest and it dominoes into more problems.
I highly doubt those mounts have worked there way loose, there should be a big thick rubber piece in there and when it is gone or worn away it would leave a gap making it appear the bolts are just loose.
u-joints gone bad can also cause more issue because it makes the pinion and drive line wiggle and cause vibration and then the pinion seal goes and that cause's the pinion to wiggle and then it goes bad, fluid leaks out and the differential wears.
at this point I would take the mechanics theory of the transfer case being the cause with a grain of salt.
every time you gas/break that front diff is going to move and make a clunk depending on how hard you gas/brake you might hear it more or less, same when turning everything twist's and moves, this goes for the engine as well and this cause's more wear on things that shouldn't move that much.
I would take a flashlight and look at your left & right motor mounts and see if there is a nasty looking stain dripping down beneath them or any liquid looking kind of oilish? it's not oil it is something else I forget the name but there is liquid inside the motor mounts and when the mount gives out the liquid leaks out and leaves a permanent stain on the metal beneath it, like it is acid or something.

 

[Doubeleive]

You can just tighten them.

mine were rotted and didn't even look a fraction as bad as his does under neath, they should not be loose unless someone loosened them or the rubber is gone.

 

[Joseph Garcia]

I had the clunk, and I replaced the slip yoke on the drive shaft line, and I replaced my differential mounts. The replacement of the differential mounts solved the clunk issue.

 

[George B]

mine were rotted and didn't even look a fraction as bad as his does under neath, they should not be loose unless someone loosened them or the rubber is gone.

 

[Doubeleive]

View attachment 392268

I respectfully disagree, movement is coming from here

 

[George B]

I respectfully disagree, movement is coming from here
View attachment 392269

I beg to differ Sir. You can see it clear as day. 0:18-0:22

 

[Doubeleive]

I beg to differ Sir. You can see it clear as day. 0:18-0:22

you are correct, my mistake, no cake for me lol
but... I would guess one of the mounts is shot and caused movement/vibration and caused the bolt to loosen or someone worked on it and didn't check there work. those bolts should not just "come loose"

 

[George B]

you are correct, my mistake, no cake for me lol
but... I would guess one of the mounts is shot and caused movement/vibration and caused the bolt to loosen or someone worked on it and didn't check there work. those bolts should not just "come loose"

It looks like someone has worked on it. You can see the passenger side bolts have been disturbed too. I would change the mounts and check all the bolts in the area like the axle flanges and the cross member. With it having been low on oil too maybe someone did a pan gasket?

 

[Doubeleive]

It looks like someone has worked on it. You can see the passenger side bolts have been disturbed too. I would change the mounts and check all the bolts in the area like the axle flanges and the cross member. With it having been low on oil too maybe someone did a pan gasket?

ya I would def be checking torque on everything under there, the rust is kind of scary.....that's a whole problem on it's own.

 

[stevedonato]

Change it and if it was me, I would do all of them, but I like to spend other people's money.

Does anybody know why all this stuff does NOT happen to GM pickups from the 90's? I have a 1996 Sierra that never had any of this stuff changed, and after all these years zero oil leaks, and original valve cover gaskets as well? 4.8L v8. Florida truck all it's life.

 

[okfoz]

nm

 

[Doubeleive]

Does anybody know why all this stuff does NOT happen to GM pickups from the 90's? I have a 1996 Sierra that never had any of this stuff changed, and after all these years zero oil leaks, and original valve cover gaskets as well? 4.8L v8. Florida truck all it's life.

a lot of it depends on and use and abuse

 

[Davheal66]

So I -think- I know where the clunking may be coming from. I got under there, and I can literally push the front hog head up about half an inch. The mount bolts that the differential is attached to have play, so do the bushings where the mount bolts to frame.I have not used 4wd since I got the truck last friday, nor do I plan to ever, this was bought as a work truck, my tools aren't heavy. I'm fine with 2wd. That said, I took it to a mechanic, he wanted to sell me on motor mounts, but this is no motor mount I'm hearing, we agreed they are bad, but not the clunk cause. Then he said the sound is coming from the transfer case and said $2500 to replace. I am willing to replace a transfer case myself, and I will for sure replace the front hog head bushings and tighten mount bolts.



My question is, can I remove the front driveshaft, and drive in 2wd, to see if the clunking persists? If the clunking stopped, perhaps all I need to fix is the bushings/mounts. On the other hand, the mechanic did say that as long as you're in 2wd, there will be no load on the front axle, which makes sense.

I did check transfer case fluid, my finger could not fit in the hole to check fluid level, so I figured I'd add some anyways to see. I was able to fill it with probably 3/4 a quart of dexron6. Rest went on me and the ground. Not sure if it'll take more, I couldn't tell if it was leaking cause it was full, or if it was leftover fluid from the bendy funnel. Put the drain bolt back on. The clunking is still there. Maybe it's not as noticeable? I think I'm saying that because that's what I really wanted to happen. No it still clunks though, either way.

The clunking comes when I'm stopping, abruptly or slowly, about 10-15ft before the actual stop. It also comes when I go from P to D, 6/10 times. Same with reverse to D, maybe 3 or 4/10 times.

Pretty sure it's already in 1st gear when I hear/feel the clunk. Transmission shifts fine, up and down, it's just hard to tell if I'm in 1st when I hear the clunk, the long pipe headers with this engine have quite a rumble. Tbh, it drives/feels like my 67 mercury cougar, if it had power steering. I like that though. I don't want to give up on this truck.

Sorry for the book. I guess my question is, can I rule out if the clunk is caused by the failure of the front differential bushings, by removing the front driveshaft? In 2wd only ofc.

Thank you for every reply, yall are saints

Hello there Doubelieve, I have information good or not. I am tearing out the suspension on my 2005 LT. I bought it in Utah last summer and toured the west for two months. It has been on blocks here in Illinois all winter out of the salt. The rubber bushings are all questionable, I chose to replace. 200k miles and 18 years old, new bushings ALL around, pitman arm, steerbox seals, and fancy paint. The clunking sound from this vehicle I thought was driveshaft related, possibly rear end. When it shifts there can be a MILD clunk, like a u joint. I believe my issue is internal play, and has not worsened. Going to service the transmission eventually. Rear end problems are common with these too, repairs parts are also common.

When bushings are worn or disintrgrating, they usually have corrosion sticking to them. Bad rubber leads to other issues.

Axles are very easy to remove with the tire off the hub. Remove 36mm axle nut, break the tie rod loose, take out a bolt, rotate and repeat 5X, move axle clear and tap from outer hub. With the removal of the front axles, the hubs should not make any noise unless moving, check for unwanted play. A debris cover should be used on the hubs to protect the splines, look at the 2wd bearings available. Disable the 4wd so it does not engage accidentally, check for play, use a supersize channel lock or pipe wrench. I'll take the axles if you'd like?

 

[DBacon]

Is the added exhaust near anything it can touch when the engine moves as you put it in gear?