What weight of gear oil, assuming, should I use for the NP-231 T case. Ive been having trouple with the vaccum actuator engagine the front axle. I replaced the switch and that work for about a week and now the problem is back so Im working if its time to change the fluid in the T case or could it be low and not allowing the switch to comback to the closed position, because the one I took out was stuck like no other. If that is it, a low oil problem, then draining and filling should work. Along with a new rear seal if thats not hard to do as it leaks a little. Any insight would be great. Thanks, Cody

 

ATF+4 in the transfer case. No gear oil.
Fill it until ATF+4 starts coming out of the fill plug.

 

ok. thanks

 

x2 on that. Use the same fluid you put in your transmission.

 

OK I was able to get the drain plug off an only about 1/3 cup of black crud came out. When I went to take the fill plug off I had to remove a vacuum thing, looked like the size of a catelope. Then I could not get the fill plug off didnt have the right size socket and the ''mm'' cresent wrench didnt fit between the case and the cab. I guess its down for the night and will have to get a new socket tonight on my way to work. Does anybody suggest I flush it out? And what could I use to do that. Thanks, Cody

 

Flush=yes what to use. i would ask at the auto parts store.

 

I would use just ATF.
Fill it up, drive it a few miles, drain it. Refill, repeat until it still looks clean coming out.
If you know of a place you can put it in 4WD, do that before draining it each time. Don't engage 4WD on pavement or other hard surface.

 

Went to put fluid in it when I topped it off it started leaking out of the front yoke!!!!! Went to see if there was and play in the yoke and it moves about half an inch in any direction. Is it expose to do that?? How hard are they to rebuild?? Today hasnt been a very good day..

 

By front yoke I assume you are talking about the front driveshaft. If you didn't have it in 4 wheel drive when you turned it by hand then the play you were feeling was in the front axle, cause the transfer case is free to turn. As for the leak, put a seal on it, its not hard to do or expensive.

 

Attached is a pic from the parts manual (you can download one: go to FAQs and scroll down for the link)
The Chrysler part number is 4338893. Expect to pay about $21 at the dealer.
You can get a better price at NAPA. Just have the serial number of your transfer case available (there should be a tag on the rear of the case with model, serial #, gear ratio, etc)

The hardest part about changing the seal is getting the nut off the yoke.
If you need a how-to on changing the seal, I can provide one upon request.