Front Differential Failure

[Lance Link]

My '99 Z-71 developed a noise from the front end about two weeks ago.  Yesterday the dealer said the front differential was bad and needed to be replaced-  $2,100!!!!  The truck has 85,000 miles on it but has been religously maintained.  Stays in a heated garage every night, complete service every 3,000 miles (oil, filer, lube front end, etc), thoroughly cleaned every Sunday inside and out, etc.  I use it to go back and forth to work and use 4WD very rarely-  only when it snows and never offroad.  

 

The customer service people at GMC said I should have changed the differential fluid every 30,000 miles, pursuant to the owner's manual.  I read mine and it says to check the level only, which I have done.  

 

Is this "Professional Grade"???  Does anyone have any thoughts on this?  Please advise.  My family has bought GMC trucks since the 50s but this is my first one.  Might also be my last one, as there have been numerous other maladies with the vehicle (bad ABS sensor, bad power steering unit @ 2,000 miles, several electrical problems, u-joint problems, etc, etc, etc).

 

Help!!!

[GnatGoSplat]

Sounds like a fluke.

I don't think front diff problems are common.  Mine has over 110k miles and I changed the front diff fluid to Mobil 1 synthetic.  I didn't have problems before, and I don't have problems now.

 

I'm sure it's a random problem, or maybe 1st model year teething problems, although mine is a 99 also.

 

As far as getting one cheaper, I saw one on Ebay last week, but unfortunately I didn't bookmark it.  I'll see if I can find it.

[Lance Link]

Thanks for the reply-  the truck's at the dealership being fixed now, but thanks for the ebay offer anyway.  I'm looking more along the lines of getting GM to help out with the repair.  I'm likely out of luck but it doesn't hurt to try.

[Lance Link]

Anyone else have input?

[RyanbabZ71]

id say a front diff failure is rare.  The rear is much more likely to go south.

 

Also its kinda hard for GM to help with the costs especially since it has 85K miles on it.  If it had 50K or less I am pretty sure they would have at least went in half.  

 

Did you call customer service besides once?  Id try again (cant hurt) ask them what page it says to change every 30K I know mine doesnt say that (even though I did change it at 30K) it only says to check.

[Lance Link]

Ryan-  Thanks for the input.  I'm pretty sure GM will tell me to screw but it still irritates me the front diff would go south after only 85K and require such a huge repair bill.  The manual does, in fact, say to merely check the fluid level (which I did) and not to change.  I could almost understand if I used 4WD often but I only use it when it snows.  If you saw the truck you would think it had 10,000 miles on it.  I'll try calling them again tomorrow and see what happens.

[Chris97K1500]

Sorry to hear about your truck, I had the same problem with my old Toyota Truck.  The front diff. went out at 75K.  I also rarely had it in 4WD.  After I talked with a few people about this I was advised to engage 4WD more than just when it snowed.  I was told I should drive about 10 miles in 4WD every thousand miles, or at least once a month.  Sorry it doesn't help now, but in the future?  Since then I've got a farm and use 4WD more often, and haven't had any trouble.  Good luck with your truck, Chris

[RyanbabZ71]

yes it is best to engage 4wd at least maybe once a month.  Best time is to put it on when it rains.  Just to get the fluid flowing through there.

[cyrylyn]

what front diff did you have?  The one I have, for 2001 IFS, sucks.  It's rated as *weak* by Off-Road Adventures, and I know a few people that have blown them up.  Weak spider.

 

I usually engage Auto when it rains, and you should change the diff fluid every 30K - I was bad, and let it go til almost 40, and there was a lot of metal filings on the plug in front, but none in the back.

[Lance Link]

Yeah, I'll be more careful to keep it engaged more often in the future.  It's used fairly frequently in the winter but rarely in the summer (I live in Maine).  

 

Not sure which diff I have-  I have the push button option on the '99 with a 5.3.  

 

I find it strange, though, that the front is shot whereas the rear diff is fine.  Neither had been serviced (I had them change the rear while it's been at the dealer).  My father and brother have the same trucks (one's a 99, the other's a 96) and they haven't changed theirs either-  they're doing so this weekend.  Live and learn-  thanks for all the input.

[Black02Silverado]

I had a 93 Sonoma 4x4 and the front diff drivers side axle seal started to leak at 90k. When I went to change it I couldn't pull the axle out. I did some searching on line and found out that it is a problem with the front axles on the S10's. The snap ring that holds the axle in broke and will not allow the axle to be removed. So basically the whole assemble had to be replaced.

 

I found a new front axle at a place in Chicago for $900. Since I couldn't afford it I went the salvage yard route and picked up the only one I could find for $300 and it had over 150k on it. I cleaned it up, replaced all the seals on it and installed it.

 

The truck had 128k on it when I traded it and the front axle was doing fine. Wasn't to hard to change out. Took me a day to swap it then off to the alignment shop.

 

Preventive maintenance is the key, I always change all fluids but in this case it didn't matter. It sucks when it happens and if you can't do the maintenance yourself due to time and such then you have to have deep pockets to get it done. They really get you in the labor.

[Lance Link]

This just in-  I spoke with another dealership who said they would simply rebuild the differential I have, not install an entirely new one.  I called them on a hunch (my father has worked with them for 30 years).  Turns out the original dealership diagnosed the "faulty" differential simply by pulling the plug and sticking their finger in.  It's likely to merely need new bearings.  It makes sense-  why would I need an entire new diff, housing and all???  They quoted me $600 to replace the bearings and reassemble the original unit.  

 

I smell a rat...

[Lance Link]

Ok-  Just an update.  I drained the front diff fluid on Saturday morning and put new stuff in.  I intended to drive it 150 miles to the other dealer near my parent's house and wanted to have clean fluid with no metal shavings.  I drained the first 1/3 of a quart into a glass jar, the rest into the oil pan.  Oddly enough, there was no visable metal shavings in the glass nor was there any on the drain plug (magnet) aside from a small amount of normal stuff.  I drove to the other dealer without drama.

 

The new dealer called me this morning and said they removed the front diff and opened it up.  Everything looked fine.  No bearing damage, no gear damage, etc.  They think the noise is coming from the left front hub and will confirm tomorrow morning.

 

Remember, the original dealer diagnosed a completely failed differential and had ordered a new one to be installed for $2,100.  My hunch is they would've noticed the noise was still there after the replacement and claimed it was a combination of the diff and the hubs and charge me even more.

 

I got a bill in the mail today from the original dealer for $67.  They're charging me a diagnostic fee.  The service guy told me himself they simply pulled the fill plug and stuck their finger in.  The invoice says the fluid was "completely contaminated with metal shavings" and a rebuild was not possible.

 

Obviously, I will not be paying said invoice.  I'll be getting all my ducks in a row over the next couple days and will be drafting a letter outlining my concerns.

 

Any thoughts/ideas are much appreciated!

[Lance Link]

Final update-  The problem turned out to be a severely worn right front hub and a lightly worn left front hub.  I had them both replaced and the truck runs quiet as a tomb now.  So much for needing a new front differential.  I have no doubt the first dealer would have replaced the diff and then, once they realized the noise persisted, they would've replaced the hubs and claimed the problem was with both.

 

Their invoice clearly states "took a fluid sample and found heavy metal contamination.  Front differential must be replaced or completely overhauled".  I have the fluid I removed from the diff and it's perfectly clean.

 

I can't WAIT to settle this with them-  they're going to think they were screwed with a dick big enough for an elephant to feel.

[RyanbabZ71]

Was it the wheel bearings?  

 

Also was the noise a loud humming?