Transfer case oil change procedure

[HereinDaRockies]

Looking to change my transfer case gear oil after grinding it while shifting from L to H. Want to flush out any potential metal shavings

The fluid spec I found cites two volumes - 1.8L and 2.64L

I am just doing a drain & fill. I am not clear what the 2.64L indicates.

Is the fluid change procedure similar to other 4x4 transfer cases? Just fill until oil comes out of the fill hole?

 

[landmannnn]

Looking to change my transfer case gear oil after grinding it while shifting from L to H. Want to flush out any potential metal shavings

The fluid spec I found cites two volumes - 1.8L and 2.64L

I am just doing a drain & fill. I am not clear what the 2.64L indicates.

Is the fluid change procedure similar to other 4x4 transfer cases? Just fill until oil comes out of the fill hole?

View attachment 7877126

There is a cooler in the front bumper, the higher quantity is if you have drained that as well as the transfer case.
You are probably best to drain the whole thing then add the specified quantity of oil.

 

[HereinDaRockies]

Are there instructions on draining & filling the t case cooling system?

 

[landmannnn]

I've not seen anything.

 

[C-Mack]

I would assume there is a 12V oil pump on or near the T-Case which is activated by either the DME or transmission software once temperature reaches a set point to push the fluid through the cooler in the bumper? If the pump is external with a plug-in electrical connector you could hook a Power Probe up to it and trigger the pump manually.

In theory, you could open the drain plug on the T-Case and let the fluid drain out first. Then you could activate the pump with the power probe and push the remaining fluid in the lines/cooler back to the T-Case so it can drain out. In reality, I don’t think you’d get every last drop out but refilling the T-Case would be the reverse process. Fill the T-Case first until oil flows out the fill port then activate the pump and the fluid level should drop down allowing you to top it up until it drips out the fill port again.

That said, I’d recommend measuring accurately the amount of oil you drain out of the system with a clear graduated painters bucket (or something similar) so at a minimum you would know the exact amount which needs to go back in. There will always be residual amounts left in the system and before draining anything make sure the vehicle is sitting as level as possible front to back and side to side.

I’ve known folks who have burned up differentials because they filled it up on a sloped driveway and thought everything was fine because the oil was leaking out of the fill plug while in reality they only got half the amount in they needed. Likewise, for vehicles with tall lifts and the axles housings have rotated in such a way the fill plug sits lower not allowing the proper amount to be put in so don’t just go off of the fill port method always measure.

Not sure what I’ve describe above will work specifically for the Grenny but it’s a way to drain fluid on systems which have cooling circuits… proceed with caution or consult the dealer first.