Front Differential Goo

[Cancerman]

With 38,000 miles on her, I pulled the plug to replace the front differential fluid with grape juice.
The magnet came out with a plug of thick gray goo (technical term) the size of the drain hole. The fluid was very thick when it started coming out. I noticed some metal slivers on the magnet as I was cleaning the goo off.
Also I only got about 1 1 /3 quart of fluid out.
This is the first fluid replacement, but I have had it serviced due to a leaking left seal and a subsequent leak that they said was from the plug.
Anyone have the same goo?

[Idle_Chatter]

Cancerman, I didn't have "goo," did have some metallic powder and filings on the magnet and quite a bit of yellow, powdery "mung" in mine (see photos in the link below). I think your goo might have been from water intrusion? especially if you had a known axle seal issue.

[10851]

Cancerman, I had the same nasty yellow flake goo come out of my 03 GMC's front diff. I changed it with Mobil 1 gear lube @ 4,000 miles. I have not had any seal leaks or water intrusion....yet. smile.gif

[GM Smitty]

I just changed out the front diff. fluid on our '03 6.0. 4000 miles on it and the drain plug was goo ridden. Replaced with Mobil 1...feel much better now. The truck did spend time in 4 wheel drive this winter while plowing.
Josh

[dmaxalliTech]

Cancer, I called GM techline today to find out if they knew of anything out of the ordinary. They agree with the rest of us. It must be some sort of water intrusion. I would say its low on lube due to the leaks being repaired but not properly topped off. I can send you an extra quart to change it again if need be. Keep an eye on it.......

[jbplock]

Here are some before and after pics of my drain plugs taken at 5kmi.

http://community.webshots.com/album/65684589edLUNA

[Cancerman]

Thanks for the responses.

jbplock, mine was even more gooy than yours and the color was lighter, I guess from the water. It did remind me of draining a lower unit on an outboard motor.

dmaxalliTech, thanks for calling the Techline. I will just get another quart locally and change it again when I get back from Shreveport next week. Time to get away and go brain dead in front of a slot machine!!

I will keep my eye on it and let ya'll know if there is anything unusual going on.

[kburati]

Just noticed this post, never thought to change my front diff. fluid even though I put Amsoil in the rear two years ago. Luckily this truck hasn't seen much 4wd use. How much does the front take? I'm going to order some more Amsoil TGR today.

[jbplock]

kburati,

Front Diff holds about 2 quarts. There is also a bulletin regarding the vent cover on the front diff. The General says you should use the “White” cover with synthetic. (My 2003 came with a black cover).
See the following threads for more info.

http://service.gm.com/gmtechlink/images/issues/feb03/TLFeb03e.html#story13
http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=7&t=004840&p=
http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=7&t=003578


smile.gif

[JimWilson]

The front diff takes about 2-3 quarts, IIRC.

[JimWilson]

Cancerman; I agree with the others -- it sounds like you got some water mixed in with your diff fluid.

[JimWilson]

I just had the dealer put on the "white" front diff breather cover because I switched to Amsoil 8 months ago. Made them do it under warranty too (something they needed to be "coaxed" into doing :D ). Still don't know why the General wants the cover changed, but now I feel better... smile.gif

[dmaxalliTech]

I just changed the diff fluids on 6.6l impala ss truck with 82k on it, it looked similer to what your describing. Mine looked the same as his with 6k on it. Seems to be common..

[Cancerman]

Changed fluid again yesterday after putting 4,000 miles on.
It drained out this time instead of plopping out in lumps like last time. The fluid was a milky color and the magnet had some goo on it, but no metal. I guess there was still enough of the goo left to discolor the fluid, but I was glad to see that there was not any metal.
Hopefully, everything will be OK now!

P.S. The cost of the grape juice at the dealer is just outrageous. $1.00 per ounce!!

[JimWilson]

That's why I used Amsoil; better stuff and only about $7 for a quart. AAMOF, I did the entire change for the same $$ that GM wanted for a single quart! Shameful...

[Cancerman]

I am about to become an Amsoil convert!

[Jomar]

Just changed the front diff. fluid and put in Amsoil, took almost 2 1/2 qts. What came out was greenish, yellow and brown and smelled awful. Only water the truck has seen is rain on the hiway. Mileage is 34,500

Jomar

[DieselBunny]

Having a hard time finding 80-90 Synthetic for the front Diff. Now 75-90 now problem. Anyone know if it'll make a BIG diff. to the diff.??
GOing to try to get the Dealer to do it for me while the Allison is being replaced tomorrow.

---->Kevin

[DmaxMaverick]

Kevin

80-90 synthetic probably doesn't exist. I've never seen it anyway. You can use syn. 75-90 (same as recommended for rear) with no worries. The target weight is the last number (90). The first number is the winter (or cold) viscosity. Your being from up north, I would recommend syn. gear oil anyway. The GM syn. will be 75-90, but about 5X the price of other good brands (Mobil-1, Redline, Amsoil), and no better, IMO. Just make sure it is GL-5 rated.

There has been some discussion on changing the vent cap on the front diff. to a later version if changing to synthetic. There is also a TSB on it. I have had synthetic in mine for over 50K with no issues at all with the original vent cap. Probably should be changed, though.

Good luck.

[JimWilson]

Sure it exists. AAMOF, it's in my shed at this very moment! :D

Personally, I wouldn't use the 75-90 in the rear -- I'd feel more comfortable with the thicker stuff (even though it's not that much thicker).