4wd pumpkin (differential) question

[Billy14]

Non-related to the DMax (although they are very similar in design) my daughter's 97 Tahoe blew out the 3 inch dia. PLASTIC threaded plug in the upper left side of the pumpkin. This took place on a 40 mile after dark trip back home during a blinding rain storm. Once she heard the whining & felt vibrations, it was too late. She was in 2wd. The plug has a rubber hose in the center which, without tracing yet, appears to be either a breather or vacuum line.

Needless to say, the unit was fried rapidly with all gear oil blown out of the huge hole at highway speed. :mad: Dealer says $3,200.00 just for the pumpkin. :mad: :mad: :mad: Had a brand new tranny installed a month ago for $2,500.00 including labor. Go Figure!

Why in the devil would they design a PLASTIC plug to metal in a unit that CAN reach high temps? By the way, our DMaxes have the same plug.

ON EDIT: Anyone know if its possible to pull the CV axles & run the truck 2wd for awhile?

Billy

[ 03-16-2003: Message edited by: Billy14 ]</p>

[jbplock]

Billy14,

Sorry to hear about your daughter's trouble… Was the lube in the differential synthetic?
The "black" vent cap is not compatible with synthetic lubes ... has to changed to "white" when using synthetic.

See http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=7&t=004761

I just changed my front Diff to Mobil-1 and I have the black cover. I had planned on getting the white one this week but now I feel more sense of urgency. :eek:

[Billy14]

Thanks jbplock,

I had the dealer change all fluids front/rear about 5 months ago before I gave it to her. Need to follow up on what they put back in. Wouldn't that be interesting.

ON EDIT: Does the synthetic have the same distinct bad smell of typical 90w gear oil? The truck reeks with the odor & can't get it to the car wash to clean it up.

Billy

[ 03-16-2003: Message edited by: Billy14 ]</p>

[Fathead]

Sorry to here about your troubles.I have changed the front axle fluid to synthetic on three GMC half ton 4x4 trucks.!999&2000 model years. Was I supposed to change to a different vent cap?
FH smile.gif

[Black Dog]

BTW, you can not pull the front axle shafts and drive the truck. The outer stub end of the axle shaft, in conjunction with the nut on the end is what holds the unit bearing assembly together. If you pull the shafts, there is enough press fit on the unit bearing assembly that it will appear that they will stay together, but if you drive the truck, you are going to lose the front tires. If you dissasemble the front shafts and just put the outer stub back in through the bearing and install the nut, you could drive it that way.

[Billy14]

BlackDog,

Thanks for the reply. If I understand you correctly, this is what I was going to try.

In other words, if I could remove the CV shaft at the outer boot leaving the spindle in place through the rotor & brg. housings I felt this might work. The problem I thought might arise, was once the boot & shaft is removed, could dirt,water enter the brg. races?

Billy

[Black Dog]

The unit bearing assembly is completely sealed. The boot only seals the dirt and water out of the outer CV joint. I think you would actually have to separate the two parts of the CV joint to keep the inner half from flopping around though, so it might be hard to keep the outer section of the joint clean. It is also a bitch to dissasemble and re-assemble those CV joints. The best thing would be to have a worn out used set of outer joints to use for this purpose.

[jbplock]

Billy14

All gear oils (mineral or synthetic) I have used have the "smell". I believe it's from the sulphur additives that give the oil it's EP (extreme pressure) lube qualities. Not sure about the GM "Grape Juice" smell. For the price it SHOULD smell good..

smile.gif

[Billy14]

Thanks To ALL! smile.gif smile.gif

Billy