So I just drained the oil out of the rear differential (with locker). The 4Runner was parked on my driveway which I think is pretty close to level...looks level. As soon as I pulled the fill plug, fluid started coming out. When I started filling the diff back up I realized there was no way I could get the 2.9 quarts in.

I would just let it leak out the fill hole until it stopped and call it good except that the original level was above that point before. It is unlikely the oil was ever changed unless the first owner did it at 30k so I think it could be the factory fill. Basically I am wondering if I should jack it up to get 2.9 quarts in and close it off or let it drain out the fill hole and have the level lower than it was originally. What do you think?

I'm leaning towards draining and filling again with it jacked up to get the 2.9 in since this is the quantity the owner's manual says should be in there.

 

If its coming out the fill hole your fine.

 

http://www.4runners.org/

 

If you drained it and then open the fill plug nothing should be coming out of the fill hole. It probably wasn't drained. Remove both the fill and drain plug and make sure it drains good. Then just fill it till it start to leak out of the fill plug. No need to fill it over that....that would be over filling it.

 

I just did this as well and did exactly what ^ poster recommended. The only one I tend to over-fill a bit is the manual tranny...smooths out the notchy-ness a bit (<1/4 qt)

 

Was the diff hot? As in, had you driven it much before the change? Hot oil expands which could cause what you described. Just fill it till it starts coming out of the hole. A lot of the "Fluid Capacity" charts/resources are wrong anyway.

 

Any chance water leaked through your breather, and into your diff?

 

Just did mine yesterday and I only got out maybe 1qt but it took nearly 5qt to fill it back up! It was parked on a little bit of an incline but I wouldn't think it would matter that much.

 

This is your rear diff?

One quart out? I would check the level often. It's gotta be leaking, good way to trash a diff.

I think the only way to get 5 quarts into a rear diff would be to stand the vehicle on the nose.

 

That's what's weird, its not leaking anywhere so I'm not sure where it would have gone. I'm pretty sure the oil is supposed to fill up the axle tubes also so that would explain the extra fluid, but why the spec is only 2.9 is another question. When I changed it i was parked in the same spot as in my avatar pic, except i backed up the driveway until the rear axle was nearly level.