# Front diff no oil/ loose bolts



## ServiceOnSite (Nov 23, 2006)

While changing my oil,tranny filter, and greasing everything under the truck today i seen a gap between the bolts and washers on the front diff. I went around the diff and tightened up every single bolt on the damm thing. Not just a half turn or so i mean several turns on each bolt. 
So i figure check the fluid. NOT A DROP! I know these things are supposed to take special fluid and ill grab some and put it in there this morning. 
How expensive are these things to have rebuilt or am i better off with buy a new one???
And on a second note, Why the hell or how the hell did the bolts come loose???

This is on my 06 GMC 2500hd. Any input would be great.


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## NICHOLS LANDSCA (Sep 15, 2007)

Just takes 75w-90 at this point I'm not sure if it would matter what you put in it. It's probably junk, wasn't it making noise?


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## chevyzrule810 (Oct 5, 2010)

There was no puddle from fluid leaking out?I would think if it didn't have any fluid it would be making a good amount of noise.If it were me I have the same truck but a chevy I would take all the bolts you just tightened up and take them all out and remove the cover.Inspect inside and see what inside looks like.Are there metal shavings in there? How does the ring and pinion look?If all checks out fine take the bolts and clean up the threads and put some lock tight on and put them back in.Then add fluid and let us know what you find.


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## NICHOLS LANDSCA (Sep 15, 2007)

chevyzrule810;1393456 said:


> There was no puddle from fluid leaking out?I would think if it didn't have any fluid it would be making a good amount of noise.If it were me I have the same truck but a chevy I would take all the bolts you just tightened up and take them all out and remove the cover.Inspect inside and see what inside looks like.Are there metal shavings in there? How does the ring and pinion look?If all checks out fine take the bolts and clean up the threads and put some lock tight on and put them back in.Then add fluid and take it for a ride for awhile.Then check the fluid and see.Let us know what you find.


He's talking about the front dif


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## chevyzrule810 (Oct 5, 2010)

I red it to quick. Add fluid and keep an eye out for puddles,and also every few days check and see if the bolts are still tight.


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## ServiceOnSite (Nov 23, 2006)

No noise at all. My skid plate was covered in oil but when i change my motor oil it spills on there so im guessing this took a long time to drain out. As soon as i get done working i gotta find out wjhat oil that thing takes and put some in there and see whats what.


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## theholycow (Nov 29, 2002)

ServiceOnSite;1393717 said:


> As soon as i get done working i gotta find out wjhat oil that thing takes


http://www.extendedgmwarranty.com/owners-manual/gmc_owner_manuals.html -> http://www.extendedgmwarranty.com/owners-manual/gmc/2006-GMC-Sierra.pdf
Front Axle (1500HD, 2500, 2500HD, and 3500 Series): *SAE 75W-90 Synthetic Axle Lubricant* (GM Part No. U.S. 12378261, in Canada 10953455) meeting GM Specifcation 9986115.


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## White Gardens (Oct 29, 2008)

Ya, I would just fill it like stated above and keep an eye out on it. If the bolts that were loose were part of the case, then I'd get either a new gasket or just use Ultra-black to seal it up good.

Does anyone know on the 06 trucks if the differential is disengaged when it's out of 4wd? I would think so as my old S-10 would engage the transfer case and also the front differential when you hit the switch, so I'm guessing it wasn't engaged in 2wd.

If that's truly the case, then I would think you wouldn't have any real damage to the front dif if it was dry, and you didn't use your 4wd very often, if at all.
....


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## 2COR517 (Oct 23, 2008)

Even when the pass side axle is disconnected, the carrier side and spider gears are spinning, along with axle shafts themselves.


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## Newdude (Dec 4, 2006)

theholycow;1393754 said:


> http://www.extendedgmwarranty.com/owners-manual/gmc_owner_manuals.html -> http://www.extendedgmwarranty.com/owners-manual/gmc/2006-GMC-Sierra.pdf
> Front Axle (1500HD, 2500, 2500HD, and 3500 Series): *SAE 75W-90 Synthetic Axle Lubricant* (GM Part No. U.S. 12378261, in Canada 10953455) meeting GM Specifcation 9986115.


Just a quick number update. 89021677 is the current number for GM 75w90 Synth. Axle Lubricant. Some dealers may stock the AC Delco branded one but its the same stuff with a different part # (88900401).


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## B&B (Nov 4, 2006)

Fill it and run it. You'll know rather quickly if it isn't going to last but I'll bet it does. The pass side axle tube holds enough residual lube to keep the tube bearings and seal lubed enough and there's a small recessed area that holds grease for the driver side bearing so they're likely all still ok as long as you haven't run it in 4WD much with it out of lube. Only real wear from a low fluid level will be on the side gears, spiders and center pin and you'd be surprised how long they'll live with no lube as long as there's no load on them.


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## meborder (Oct 26, 2011)

Maybe there is something about the 06's i am unaware of, but the only time the front center diff would turn is in 4wd.

IIRC the wheel bearings are a sealed unit bearing, and unless it is engaged the hubs should spin free, and the half-shafts should never turn. If that's the case, unless you were running it in 4wd a lot lately, the front diff may never have even turned before you caught it.

I have heard that there were a few years in the 2000's for which this is not true, and perhas 06 was one of them, i guess i'm not sure.

but i agree, the only thing you have to lose is a few bucks worth of gear oil. fill it and run it ... then decide from there.


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## chevboy167 (Dec 7, 2011)

i just had the front diff rebuilt in my 99 Z71. it made noise for 6 yrs! started out very little, but got worse over the years. it was never low on fluid, as i changed it twice a year. the side bearings in there are locked in preload pressure by a spyder washer. metal tabs bent over to keep the nut from back off. the washer tabs broke on mine and lost the preload! also 2 rollers of a bearing had chunks out of them. got lucky didnt need any gears. they all were great. my maintenance buddy at work did a great job and did it in a hurry! like 4 hours! all new timken bearings and seals. $420.00... whatta deal!


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## 2COR517 (Oct 23, 2008)

meborder;1394742 said:


> Maybe there is something about the 06's i am unaware of, but the only time the front center diff would turn is in 4wd.,,,,.


The IFS GM trucks do not have lockout hubs at the wheels. CV shafts, and everything attached to them, rotate any time the vehicle is in motion.


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## ServiceOnSite (Nov 23, 2006)

Filled and changed the fluid twice on the front end and it keeps coming out black just after running it a little while. Im going to keep topping it of over the winter as right now i just donr have any time to drop the axle and reseal it. See how this works.


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## chevyzrule810 (Oct 5, 2010)

good luck hope it last through the winter


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## 2COR517 (Oct 23, 2008)

ServiceOnSite;1400213 said:


> Filled and changed the fluid twice on the front end and it keeps coming out black just after running it a little while. Im going to keep topping it of over the winter as right now i just donr have any time to drop the axle and reseal it. See how this works.


If you want to give it a good scrubbing, use some Automatic Transmission Fluid in the differential. Run it a few days. Engage 4wd a few times for a short period to ensure the ring gear, carrier, pinion and bearings get a good coating.

Let it drain, as long as you can. Fill with some cheap dino 80W-90, run a few more days, then drain & refill with the synthetic 75W-90


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## meborder (Oct 26, 2011)

2COR517;1400332 said:


> If you want to give it a good scrubbing, use some Automatic Transmission Fluid in the differential. Run it a few days. Engage 4wd a few times for a short period to ensure the ring gear, carrier, pinion and bearings get a good coating.
> 
> Let it drain, as long as you can. Fill with some cheap dino 80W-90, run a few more days, then drain & refill with the synthetic 75W-90


Agreed on the flush.

you could also add kerosene to flush, kero is an awesome solvent. I would suggest a "no load" run if you were to use kero. Perhaps idle it in 4wd on jackstands for a while, then drain and refill as posted above.

ATF is probably the 2nd best solvent to use, but probably much safer.

keep us posted!


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## ServiceOnSite (Nov 23, 2006)

Lost about a 1/4 of a quart from then till now. I suspect that its coming out of a few of the top bolts i just couldnt get to. As soon as spring hits i will drop the whole thig out and rebuild it with new seals and such. I just cant get over the no noise part of this.


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## chevboy167 (Dec 7, 2011)

sooo.... the two front diff case halves were not sealed? all the CASE bolts were loose? or do you mean the diff mounting bolts with nuts, were loose? if its the case halve bolts, then WOW! i bet the inerds are fried!


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