# 2500hd 4wd noise, Help!!



## 04hd (Jan 3, 2013)

Need some help. I have an 04 2500hd Reg cab long box 4x4. My question being noise when in 4wd. It is quiet when in 2wd except when turning. during turns(sharp turns) I have a grawl (rear end)?? I have done wheel bearings/hubs 4,000 miles ago. My question is could it be u joints in front drive shaft, a front differential problem or a transfer case problem.? Some further info... When I did my front wheel bearing/ hubs I changed oil in front and rear end. I was informed by the head mechanic at gm dealer to put one bottle of slip additive to the rear end. Owned ruck since new and have 63,000 miles on it I have noticed some noise since new but it has gotten bad in past 2 months. The noise gets worse with speed. It doesnt make more or less noise when turning with 4wd engaged. I have also noticed more of a "clunk" if shifting from reverse to drive while in 4wd. Sorry for the life story Id just hate to throw money at it and have fixed multiple things for no fix of the problem. Thanks to every one in advance for your help!


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## wcup102 (Jan 29, 2012)

Doesn't that have CV joints in the front? If so it may be bad CV joints or a short axle problem. The other noise when shifting sounds like possibly u-joints in the driveline. I am no mechnic but have had plenty of experience with GM's and replacing short shafts and CV's


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## hobbyjeep (Dec 11, 2003)

Tech said to install limited slip additive....did you install it? Can't tell from your write up. 
That axle requires it or you get chatter.


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## theholycow (Nov 29, 2002)

Responding piece-by-piece...hope this helps:



04hd;1577021 said:


> noise when in 4wd. It is quiet when in 2wd except when turning. during turns(sharp turns)


Can you clarify? First it sounds like you're talking about 4WD, but then it sounds like you're talking about 2WD. In which mode does it make the noise?



> I have a grawl (rear end)?? I have done wheel bearings/hubs 4,000 miles ago.


If the 2500's front unit hub/bearing modules are similar to the 1500's, I wouldn't count them out. New ones can come defective (especially aftermarket brands, but even OEM), can very easily be installed with the wrong preload, and even if neither of those was the case they can still randomly fail very early. Worse, the symptom can be different every time, and they can pass the usual tests (jack it up and try to rock the wheel, then try to spin it, etc) while still being failed. That sucks.



> My question is could it be u joints in front drive shaft, a front differential problem or a transfer case problem.?


In 2WD I don't think it could be any of those things.



> I was informed by the head mechanic at gm dealer to put one bottle of slip additive to the rear end.


Did you do any research to verify this? I seem to remember that GM's locking and limited slip differentials do NOT call for friction modifier additives, just straight synthetic differential oil.



> The noise gets worse with speed. It doesnt make more or less noise when turning with 4wd engaged.


That is consistent with wheel bearing failure. 



> I have also noticed more of a "clunk" if shifting from reverse to drive while in 4wd.


In general the clunk is pretty common and the official solution is to grease the driveshaft slip yoke while a more permanent solution I've seen on forums is some clamps added to the leaf springs to reduce driveline slop. I'm not sure what it might mean for it to be exacerbated by 4WD...perhaps front U-joint?



> Sorry for the life story Id just hate to throw money at it and have fixed multiple things for no fix of the problem. Thanks to every one in advance for your help!


Agreed. If you can't figure it out diagnostically, rather than giving up and throwing parts at it I'd say to locate a driveline diagnostic expert and pay him instead.


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## NBI Lawn (Oct 15, 2007)

I would go with defective Hub bearing. Jack it up and check for play.


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## 04hd (Jan 3, 2013)

Yes I did the whole little bottle. Used synthetic oil also!


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## 04hd (Jan 3, 2013)

Dear holycow 
1. I am talking about 4wd and stating that in 2wd when I turn sharp in a parking lot etc. I have a grawl noise coming from rear end? when I changed oil in it I used synthetic with a bottle of slip additive.
2. Im debating taking them off and seeing how they spin by hand.
3. I contacted another dealer 20min from the first and talked to them and I was told it doesnt NEED it but its surely not going to hurt anything. He said "I run it in both my trucks which have same rear end as yours"
4. Im going to stop into a truck place near by that does a ton of drive line work and have one of those guys take it for a spin and see what he thinks.
I thank you very much for your response


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## 04hd (Jan 3, 2013)

Front differential got rebuilt as well as new u joints in front shaft. I had them do rear u joints aswell. Got em greaseble!!Thumbs Up The guy who test drove it said he drove it scratched his head drove it again then did u joints in front as being the cheap fix and that didnt do it so he figured it had to be the differential. Pinion was cracked and carrier bearing was shot. How is something id like to know the truck is surely not beat. Always had oil in it. guess its true that if its man made it will break.


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## chevboy167 (Dec 7, 2011)

Good to hear you got her fixed. My 99 1500 had front diff bearings crap out. It started growling 8 yrs ago. Little at first then thru the yrs got worse. Finally yanked it out and had a chevy guru rebuild it. The side bearing preload lock washers had broken the tabs. Side bearings lost their preload but didnt hurnt any gears! Got lucky! He said he sees this all the time. Cheap bearings and lock washers. Bearings had chunks missing out of the rollers. All Timken bearings now and quiet as church mouse!


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## OhioPlower (Jan 13, 2004)

How much did it cost to rebuild your front diff? My 04 has similar symptoms


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## 2006Sierra1500 (Dec 28, 2011)

chevboy167;1581729 said:


> Good to hear you got her fixed. My 99 1500 had front diff bearings crap out. It started growling 8 yrs ago. Little at first then thru the yrs got worse. Finally yanked it out and had a chevy guru rebuild it. The side bearing preload lock washers had broken the tabs. Side bearings lost their preload but didnt hurnt any gears! Got lucky! He said he sees this all the time. Cheap bearings and lock washers. Bearings had chunks missing out of the rollers. All Timken bearings now and quiet as church mouse!


Sounds like what happened to my 2000 2500 Silverado before I sold it. At that point I'd had it for 10 years and 54k with an 850 lb blade on the front, so it wasn't worth fixing and down the road she went.


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## 04hd (Jan 3, 2013)

I would have to double check but I had around 1200 in to it. That includes labor. My final bill was more but that was for u joints and some brake work.


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## OhioPlower (Jan 13, 2004)

Yeah that's about what I figured I'd have in it


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## 04hd (Jan 3, 2013)

Be sure to have who ever does it price a reman front differential. Depending on how bad stuff is that could be a much cheaper route (mainly on the labor).


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