Rear Differential Lube Change...

[HillHound]

Finally did this job today at almost 15000 miles since I've done a few thousand miles of light towing.   I bought the overpriced grape crap from the Chevy dealer at $20 per quart along with a new gasket.  There was only a little bit of grime on the magnet in the cover and I sprayed a can of brake cleaner into the gears.  No problems other than I splashed brake cleaner into my eye :angry: .   Probably won't need to do this again for a long time but the first 15000 miles should be a good break-in period for the weight of the stuff I've towed

 

Has anyone else that's done this had any trouble with the gasket leaking after removal?  I drove it about 20 miles and so far so good.

[MountaineerTom]

I did mine this past spring/summer, I think in the lot to mid 20,000 miles range.  I'd have to look in my maintenance notebook that I keep in my truck to be sure.  Havn't had any problems with the gasket leaking.  I used Valvoline synthetic in the rear though.  I bought fluid to change the front out too, but still havn't got around to doing it yet.  

 

My magnet had a good bit of junk on it.  Here some pics of how nasty before, and how clean after.  

 

http://tommy3z71.homestead.com/diff_cover.html

[HillHound]

Thanks Tom.  That's just about what my magnet looked like, maybe not quite as much.  I was probably stupid for buying the GM axle lube but a few people told me the locking diff's proper function depends on the specifications of the fluid.  How much did the Valvoline lube cost you?

 

When I change out the front I will definitely use some cheaper stuff from the local auto parts shop.  I changed the transfer case fluid a few days ago and I did use the GM brand fluid the manual specifies but it was only $3.80/quart (it took a little over 2 quarts).  Part of the reason I even changed that was to see if it helps witht the driveshaft squawk noise I an getting.   ???

 

BTW-the Chevy garage here wanted to charge $70 some dollars PLUS fluid/gasket to change the rear diff fluid!  As if the price of their gear lube is'nt enough of a ripoff!

[RyanbabZ71]

BTW-the Chevy garage here wanted to charge $70 some dollars PLUS fluid/gasket to change the rear diff fluid!

 

Wow thats half of what the local dealer wanted.  I did it myself with the gm fluid and gasket.  

 

I changed mine at 18K and currently have almost 24.  No leaks as of yet (knock on wood).  Next time i change it i would probably use Mobil 1

[THE BIGPUNN]

i plan on doing mine this spring, now is a good chance to ask you pros some questions. how much is the gasket? do you have to put sealant on with the gasket? do you use a gasket scraper to remove the old gasket? and do you add anyother gear fluid besides the regular gear fluid? thanks guys.

[RyanbabZ71]

i plan on doing mine this spring, now is a good chance to ask you pros some questions. how much is the gasket? do you have to put sealant on with the gasket? do you use a gasket scraper to remove the old gasket? and do you add anyother gear fluid besides the regular gear fluid? thanks guys.

My gasket cost like $9 (kinda overpriced but no one else had it)

 

i used a sealant on the advice of my father who is a mechanic.  It was some bluish green stuff

 

gasket scraper?  You can use any kind of scraper.  Nothing special is needed.  I forget what i used

 

just 1 type of gear fluid (synthetic stuff).  The old trucks you had to add a modifier but not with the new stuff

[MountaineerTom]

How much did the Valvoline lube cost you?

 

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I changed the transfer case fluid a few days ago and I did use the GM brand fluid the manual specifies but it was only $3.80/quart (it took a little over 2 quarts).  

The Valvoline synthetic cost me $9.50 a bottle at CarQuest.  I'm sure you may know, but the front doesn't require synthetic fluid, so I bought the regular gear oil for the front diff.  It was only $3.50 a bottle at NAPA.

 

That's not too bad for the transfer case fluid.  I may do that myself someday soon, just o get some fresh stuff in there.  

 

I don't remember exactly how much my gasket was from the dealer, but it was around what Ryan paid.  And I used a thin layer of gasket sealant as well.  No other additive used with the gear oil.

[RyanbabZ71]

Hey Tom for future reference do you have any info on the transfer case change?  Pics or anything like from the manual?

[HillHound]

i plan on doing mine this spring, now is a good chance to ask you pros some questions. how much is the gasket? do you have to put sealant on with the gasket? do you use a gasket scraper to remove the old gasket? and do you add anyother gear fluid besides the regular gear fluid? thanks guys.

FYI:

Gasket is GM part#26066456 cost $5.13

 

Rear axle fluid is GM part#12378261 cost was about $25.00 per quart but I  complained and the parts guy gave them to me for $20.  You need to buy 3 quarts of whatever brand you decide to use.  Took about 2.5 quarts.  And it stinks!

 

I didn't put sealant on the gasket but it probably would be a good idea-I'll find out I guess   .  I just used an old putty knife and brake cleaner to remove the old gasket, then I sprayed the rest of the brake cleaner into the gears to clean them.  You'll need a fluid transfer tube or a bulb pump to put the new fluid in-the filler hole is kind of close to the bottom of the bed and it's tight fit for a quart bottle.

 

Half hour job if you don't spray brake cleaner into your eyes!!  In case anyone wonders...it burns!!  :0

[01z71]

When I changed my fluid I just took out the bottom bolt and drained the fluid.  I then put new fluid back in.  Does it make a difference if you don't take the cover off?  I think I must have missed a step then.   ???

[RyanbabZ71]

well there is junk (metal shavings and such) around the magnet on the rear diff cover.  By not taking that off means that you didnt get that out.  I wouldnt say you missed a step but next time you change it i would suggest taking off the rear diff cover and cleaning around the magnet

[01z71]

Thanks, that's what I'll do.  I'm always looking for a good excuse to do or re-do something for a good weekend project.

[MountaineerTom]

Hey Tom for future reference do you have any info on the transfer case change?  Pics or anything like from the manual?

I havn't changed mine yet, but I do have a Haynes manual.  I'll see it it has any good pics, and if it does, I'll scan then and send them to you.  

[MountaineerTom]

Ryan,

The procedure is pretty simple.  Should be easier than changing the motor oil.  The Haynes manual only had one pic, and it wasn't much.  So I just went out and took pretty much the same pic they did.  I'll just copy what the manual says.

 

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Transfer case lubricant change (4WD models) (every 60,000 miles or 48 months)

 

1. This procedure should be performed after the vehicle has been driven so the lubricant will be warm and therefore will flow out of the transfer case more easily.

 

2. Raise the vehicle and support it securely on on jackstands.

 

3. Remove the filler plug from the case (see illustration)

 

4. Remove the drain plug from the lower part of the case and allow the lubricant to drain completely.

 

5. After the case is completely drained, carefully clean and install the drain plug.  Tighten the bolt securely.

 

6. Fill the case with the specified lubricant until it is level with the lower edge of the filler hole.

 

7. Install the filler plug and tighten it securely.

 

Drive the vehicle for a short distance and recheck the lubricant level.  In some instances a small amount of additional lubricant will have to be added.

 

<--- Back of Truck.    Front of Truck--->    

 

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For me, I wouldn't drive it too much, that way you don't get burned with the fluid.  I don't plan on using jack stands.  I can get under there with out them and my driveway has a little incline, so the fluid will drain easily.  I'd check the manual to see if that fluid level is corret.  And if you have a skid plate, remove it for easier access and so the fluid doesn't splash all over it while draining.

[01z71]

All right, I think I'm gonna redo my axle fluid change this weekend.  Hillhound did you have any problems with leaks with no gasket sealent.  What type / kind of gasket sealent should be used.  Thanks guys.