Question about my T-case

I'm confused and need some clarification please :?

I've attached a picture of my transfer case, which I believe is the model 18. I know that the bung on the bottom of the case is the drain, and I thought that the square plug on the side up by the frame rail was the filler/inspection hole?

The reason I'm asking is because my speedometer cable has been leaking a lot of oil lately (see pic) and I wanted to see how low the fluid level was. So I unscrewed the square plug, and even though the Jeep is on a level surface, fluid started gushing out of the filler hole.

I've gone through my Hanyes manual and it just says to "fill the transfer case to just below the filler hole", so...how did the case get so full, and how is it still full with all the leaking:? :? :?

Thanks,
Allan

 

You are correct. That is an 18 transfer case. The bung on the bottom is indeed the drain and the square headed plug is the fill. It's supposed to be filled to the bottom of the fill plug hole. Probably the oil has transferred from the transmission as T-90's and some other transmission and the 18 transfer share an oil passage between the two. I'd check the level in the transmission, I'll bet you'll find it over full. Could be someone overfilled the transmission and the excess found its way to the transfer case or could be there is water in one, the other, or both. I'd recommend draining them both and refilling with clean 85w90 gear oil. Then you know exactly what you have. By the way, the oil will float on the water giving the impression that the oil is way too full. Nickmil

 

So if I pull the plug on the bottom of the transfer case, will it drain the transmission too, or does the oil journal between the two only come into the equation if the transmission is overfilled?

Allan

 

Thanks for the help guys, now I have a better understanding of what's going on in there.


Allan