So, my tcase's front seal is leaking, how do i replace it?/how easy is it?

[Dabba]

So, i get under my truck to fix a dent i put in it offroading and see a small pool of ATF in my driveway, the np208 apears to be leaking from the front output shaft. All i have is normal hand tools and a driveway, no garage and im a newb. How easy is it to fix it and how do i go about doing it? Im assuming its a gasket/seal, Do i need to drop the shaft out and do i need any special tools like torque wrenches or anything? Thanks

Also, i just need to drain and fill the case right? Tranny fluid dosnt mix with tcase right? How much does it hold? I also noticed it only leaks when its running, not when it sits. I have used the 4x4 but not recently and its been leaking from the front.

 

[toomany]

Your gonna have to pull the shaft out and remove the yoke to get the seal off. I don't recall what the size of the nut is on the yoke, I think it's around 1 1/16 (1 3/16?) I know you will want at least 1/2" drive stuff to remove it...an impact gun is even easier. Put the t-case into 4 and block the rear wheels when loosening the nut. The only special tool you may need is a seal puller, but you can get by with a screwdriver. Not sure how much the 208 holds.

 

[Dabba]

I looked at the parts and the diagram, how do you take off the driveshaft? The 4 bolts on the yoke right? Once thats done how do you get the yoke out then?

 

[Lunatic]

Its simple

1. Drop the four 5/8" bolts holding your driveshaft to the transfer front output yoke. With a long screw driver (something to pry with), pry the shaft forward gently. Remove the front driveshaft retainging straps (7/16" socket) and you can put the shaft to the ground. Tape the ends of the universals to prevent the caps from falling off/out - Just wrap tape around the driveshaft, covering the caps.

2. Grab a 1/2" pneumatic impact and a 1-1/8" socket, remove the transfer front drive shaft yoke nut.

3. Remove the drive yoke by simply pulling it out with your hand, rock it back and forth if necessary to help it slide on the transfer spline while pulling.

4. Remove your forward output seal. Be very careful not to gouge the transfer seal housing with the prying tool. Inspect the seal housing once the seal is removed for scores, gouges, etc - Use emery (spl ?) cloth (metal sanding paper) to clean up the transfer seal housing rim of any noted scores and remnant sealants etc.

5. Re-install the new seal. Set it flush to the transfer seal housing lip and gently tap it with a small (8oz-ish) hammer around the rim of the seal. It can be tricky getting the seal started - It will (WILL) look like it started, then pop out on the opposite side of your next tap of the hammer. Once you do get it started though, simply coontinue around the edge and evenly tap it until it is flush with the transfer housing edge.

6. Re-install your forward output yoke. Be sure to install the starred rubber grommmet before installing the actual yoke. When installing the yoke to the splined shaft, some people use oil, to lubricate the seal as the yoke is inserted. I prefer a light coat of grease - It remains applied (Oil will squeegy off) and allows the seal to actually seat to the yoke shaft without running hot. This only serves as another preventive measure to the new seal leaking. Use a lubricant on the yoke shaft before inserting it into the tranfser on the splined shaft.

7. I apply a bead of RTV around the inner edge of the nut holding the yoke to the spline shaft. It will all most likely squeeze out when you torque the nut, but what doesnt do so will seal to the star washer you installed to the spline shaft before installing the yoke - Another preventive measure of leaking.

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Noting you only have "normal hand tools and a driveway", the yoke nut may present a challenge.

The transfer and transmission both run ATF (auto transmission fluid). Simply drain and refill. Approximately 10 pints / 5 quarts

The seal wont leak while sitting still - When the driveshaft rotates, it allows seap-age of fluid thus showing up on your driveway.

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This is a super simple task. Dont be intimidated, take your time, and be safe about what and how you perform the task. With that said - Good luck !!!



Lunatic
Ft Hood, TX

 

[Dabba]

see next post \/

 

[Dabba]

hey sorry, didnt see that post. Very awesome instructions. Yeah i saw the yoke bolt is torqued to 100 something pounds so that may be interesting. Whats RTV? And the front shaft wasnt spinning, i was driving around in 2wd with the fronts unlocked, guess the leaks that bad. I did use 4wd a few days ago but i wasnt that hard on it. The PO told me the tranny and tcase had only about 20k on them, why would the front seal leak so early in its life? Its gonna be cold too, guess ill see what happens. Really? 5 qts of atf for the tcase? Tcase and tranny dont share atf right?

 

[toomany]

RTV=Room Temp Vulcanization(sp) Basicly it's silicone that cures at room temp.

The seal could have gotten some dirt under it, a rough spot on the seal surface of the shaft, or even the front bearing is starting to go.

The tanny and t-case don't share their fluid.

 

[Dabba]

thanks maybe my DW shook things around too much, ill be fixing that today

 

[Dabba]

hey, just thought of this, whats going to keep the yoke from spinning while im trying to loosen the bolt? thanks

 

[onetonbb74]

If your in 4x4 high range w/ the rear wheels on the ground chalked, it wont move.

 

[Dabba]

thanks, im sure if i run into an issue ill be posting

 

[toomany]

hey, just thought of this, whats going to keep the yoke from spinning while im trying to loosen the bolt? thanks

In theroy, if you have an automatic...the park pawl should stop it from spinning (provided you are in 4hi/lo). But it still isn't a bad idea to block the rear tires.