This is a write-up on how to replace the Output Shaft Seals on your Transfer Case. Gear oil leakage from these seals is a common problem on 3rd gen 4Runners, but there is not much information on the replacement procedure available on the web for DIY’ers. I decided since I was doing the job, I’d go ahead and write it up, especially since there doesn’t seem to be any other formal write ups available.

My 2001 4Runner recently developed a relatively fast leak from the Front Output Shaft Seal on the Transfer Case. My 1997 has had a slow leak from the Rear Output Shaft Seal for some time. I replaced the front output seal on the 2001 today, and the write up follows below. When I get around to replacing the rear output seal on the 1997, I will add that procedure to this write up, although it should be very similar to the front.

First, here’s the leak I’m describing:





Next, let’s start w/the details on what you’ll need and some links I found helpful:

Tools:

3/8” Ratchet
3/8” 3 inch extension
3/8” 12 inch extension
3/8” to 1/2” drive adapter
1/2” to 3/8” drive adapter
1/2” drive breaker bar
Large Flathead Screwdriver
7mm Wrench
Seal Puller
Hammer
1/2” drive 30mm Socket (I used a 1 3/16”socket, it’s the same as a 30mm)
1/2” Drive 24mm Socket
3/8” Drive 14mm Socket
3/8” Drive 12mm Socket
1/2” Cold Chisel
3/8” Center Punch
1/2” Drive Torque Wrench
Fluid Pump
2 Quarts of 75w90 Gear Oil
14 oz tube Lucas “Red N Tacky #2” Multi Purpose EP Grease or Equivalent
Grease Gun
Drain Pan
Paper Towels
Brake Cleaner



Toyota Parts:

90311-41012, Seal Type T Oil ($10.27)
90179-22016, Nut ($2.95)

Torque Values:

Transfer Case Fill Plug -27 ft./lbs
Transfer Case Drain Plug - 27 ft./lbs
30mm Output Shaft Nut - 87 ft./lbs
Driveshaft to Companion Flange Nuts - 54 ft./lbs
Transfer Case Skid Mounting Bolts - 28 ft./lbs
Grease Fitting - barely tight, no value in FSM

FSM Links:

Transfer Unit Components - http://www.ncttora.com/fsm/1996/SIL/...rauni/comp.pdf

Transfer Assembly Components - http://www.ncttora.com/fsm/1996/SIL/...raass/comp.pdf

Oil Seal Components - http://www.ncttora.com/fsm/1996/SIL/...ilsea/comp.pdf

On to the work itself:

1. If equipped remove the plastic undercarriage cover beneath the driver’s side door using a Ratchet & a 12mm socket.



2. Remove the four bolts securing the Transfer Case Skid Plate using a Ratchet & a 12mm Socket.





3. Clean the driveshaft where it meets the companion flange, and clean the companion flange itself. Then mark the relationship of the two so that you can re-assemble them exactly as they are.



4. Use the 3/8” drive 12 inch extension to secure the driveshaft while you remove the four nuts holding the driveshaft to the companion flange using a Ratchet, 3” extension, and a 14mm socket (A breaker bar helps too). You secure the driveshaft by sliding the extension through the U-joint so that it hits the Transfer Case, preventing the assembly from rotating while you loosen the nuts.



5. Now that the driveshaft is unbolted from the companion flange, you will need to move it forward by telescoping the sleeve yoke over the front propeller shaft. There is pressurized grease between the two that will prevent you from doing so.

In order to relieve the pressure, and allow the driveshaft to collapse forward, you will need to remove the grease fitting pictured below using a 7mm wrench.



As you collapse the front driveshaft, thick grease will begin to spew from the hole where the grease fitting was installed.



Collapse the driveshaft enough that you can get it off the bolts on the companion flange and allow it to rest on the cross member near the fuel filter. Once you have set the driveshaft aside, you should be seeing this on the transfer case, this is the 30mm staked nut, nestled inside the companion flange.



6. Using a 24mm Socket and a Breaker Bar, loosen the Transfer Case Fill Plug, but do not remove it completely. Situate your drain pan under the Transfer Case. Next, use the same socket to remove the Transfer Case Drain Plug. By leaving the fill plug in, you will prevent the gear oil from shooting out of the drain plug. It should drain smoothly into the drain pan. (Note: This step could alternatively be done first)



7. Un-stake the 30mm Staked Nut. This is the hardest part of the job. This involves hammering a punch or chisel into a small notch in the Transfer Case Output Shaft. I purchased a 3/8” center punch & 1/2" cold chisel to un-stake the nut, but they were causing damage to the Shaft, so I used an angle grinder to modify the center punch.

Modified like so I was able to easily un-stake the nut by driving the tip of the modified tool into the notch.





8. Remove the 30mm Staked Nut. First, take the 4 nuts that held the driveshaft to the companion flange, and thread them onto two neighboring studs on the companion flange. The purpose of this is to protect the threads on the studs while you break the 30mm nut loose.

Secure the companion flange as pictured below, by wedging the 12” extension between the protected studs, and against the Transfer Case. Using the 30mm (or 1 3/16”) 1/2” drive socket, and a 1/2” drive breaker bar, loosen the 30mm nut.



9. Grab ahold of the companion flange and pull it forward. It should pull right off the output shaft.



With the 30mm nut and the companion flange removed, you can see the damage I did to the output shaft. It was very minimal and did not affect the thread engagement of the 30mm nut. I’m not sure how to un-stake the nut without causing some small degree of damage.

AND THERE’S OUR CULPRIT!!!



10. Take note of how deep the seal is installed into the Transfer Case housing. You want to make sure that you install the new seal at the same depth.



YOU’RE HALF WAY THERE!

I took the opportunity to take a picture of the outer seal. It rests within the companion flange and its quite a bit smaller than the inner seal. Mine was dry as a bone, so I didn’t replace it.





These are the parts you’ll be replacing. I confirmed with the Toyota Dealership that these part numbers are the same for both a 1997 and a 2001 4Runner. I am not sure if they are common to ALL 3rd gen 4Runners, so do your homework when you order parts.

The Front Output Shaft Seal







A new 30mm Staked Nut (By the way, some people like to re-use these… the FSM states they are a non-re-useable part, so I did not re-use mine.)



11. Place the new seal. Before you insert the seal into the case, make sure to clean the inside of the case where the seal sits. If you’ll notice in the picture below, the seal has a funnel shaped extension on the front side that prevents you from using a seal driver to seat it. Aside from that, the output shaft is in the way. I simply coated the outside edge in gear oil and placed it carefully by hand. I made sure to press it in slowly and evenly.



12. Clean up the companion flange. Make sure that the surface pictured is nice and clean and that it does not have any damage. This is the surface that the seal rides on, and if it is damaged, it could lead to future leaks.



13. Using the methods discussed above for securing the companion flange, install a new 30mm nut. Torque to 87 ft./lbs.



14. Using a center punch and a hammer, stake the new 30mm nut.



15. Using the marks you placed earlier, re-install the driveshaft onto the companion flange. Make sure that everything is aligned, then re-install the 4 nuts that secure the driveshaft to the companion flange. Torque the nuts to 54 ft./lbs using the methods discussed above for securing the driveshaft.



16. Re-install the Transfer Case Drain Plug. Torque to 27 ft./lbs.

17. Using a fluid pump, re-fill the Transfer Case with 75w90 gear oil.

18. Re-install the Transfer Case Fill Plug. Torque to 27 ft./lbs.

19. Re-install the grease fitting into the front driveshaft. As mentioned earlier, I couldn’t find a torque value for this fitting, but it is very small, so I tightened it just past the point where I felt it snug up.

Using your grease gun, re-fill the space between the sleeve yoke and the propeller shaft. Just shoot a bunch of grease in there, don’t worry about over filling it.

To get the amount of grease in the driveshaft just right, remove the grease fitting again, and allow the grease to ooze out until it stops, then re-install the grease fitting. This will relieve the pressure in the driveshaft and leave it with just the right amount of grease to fill the gap with no residual pressure.

This is the grease I used:



20. Hit everything with brake cleaner so you can keep an eye out for ongoing leakage.

21. Re-install the Transfer Case Skid Plate & the plastic undercarriage cover.

DONE AND DONE!

I finally got around to replacing the Rear Output Seal on the Transfer Case of my '97 4Runner today.

The job was more/less the same as replacing the front seal, with a few exceptions. I had been working on my Wife's 4Runner yesterday and the day before, and taking some pictures along the way, and as a result I left my camera in her center console. Well, she was at work today, with her 4Runner, so I wasn't able to take any pictures while replacing the rear seal.

Before I forget, here are the mental notes I took along the way:

1. The nuts that secure the rear driveshaft to the companion flange @ the transfer case cannot be removed with a socket. The design of the double cardan joint @ the front of the rear drive shaft prevents doing so. I tried short and deep sockets, a universal joint, 6 and 12 inch extensions. It just wasn't happening.

2. You cannot use a 12 inch extension through the couble cardan joint to keep the driveshaft from rotating while you remove the driveshaft > companion flange nuts.

3. You must have one rear tire off the ground, the emergency brake OFF, and the transmission in nuetral in order to spin the rear driveshaft so that you can access all 4 of the driveshaft > companion flange nuts. BE SURE TO CHOCK THE WHEELS, because when you do this, there is nothing to keep the vehicle from rolling.

4. Once you have the driveshaft rotated to where you can access two of the driveshaft > companion flange nuts, put the rear tire back on the ground and set the E-brake. This will secure the driveshaft so that you can remove the driveshaft > companion flange nuts.

5. After you get the first two, see step 3 and rotate the driveshaft so you can get to the other two. Repeat Step 4.

6. After all the driveshaft > companion flange nuts are removed, you'll need to remove the zerk fitting that is just rearward of the slip yoke on the rear driveshaft. This allows the pressurized grease to escape when you collapse the driveshaft rearward and off the companion flange studs.

7. After you've got the driveshaft separated from the companion flange, you remove the 30mm staked nut using the same technique described in the write-up for the front seal.

8. The rear seal was a little tighter fit, so I used a small wood block and a rubber hammer to softly and evenly tap it into place.



The rest of the job goes basically the same as the front. Good luck!



Part numbers for the rear:

90311-41007 - Seal, Type T Oil (This is the main output shaft seal on the rear, and is definitely different from the front)

90179-22016 - Nut (This is the 30mm nut, and is the same as the one on the front)

90312-23001 - Seal, Type V Oil (This is the seal that goes in the rear companion flange, it is not the one that typically leaks and should not need to be replaced)

good ****!


you are in new mexico too???? damn, im surprised to see so many new mexico members on here. when i lived there i was the sole member on every car forum i was on, lol! ill be out there sometime within the next six or so months.

Yet another great write-up from BigFish, nice job!

This one gets bookmarked. As always, thanks for the write up. I have to ask, what is with the #'s underneath?

I think there is a special SST tool instead of having to grind down the chisel; the same tool may be found on the Snap On/Blue Point truck. If I find it, I'll post a pic.

Fantastic write up!

Yes sir, born and raised. How long ago did you live out here?

Thanks Brian. And thanks for reading. I'm sure you've seen/done this job before, let me know if you have any suggestions for edits/additions.

The #'s underneath (I think you mean the writing in sharpie marker) are dates and mileages when the fuel filter has been replaced.

Let me know if you find that tool. When I go to do the rear I'm going to modify another punch to work a little better, but I'd love to have the RIGHT tool for the job.

Thanks Volley.

Friggin' awesome! Well done.

This is incredibly helpful. I say between this write up, the Tundra brake upgrade, and others you have done I vote you the 3rd generation member of the year!!!

All joking aside I am genuinely thankful to you and all the others who go above and beyond to help out other members. You guys are what makes this feel like a real community.

Keep up the good work.

Yeah no kidding!!! BFAD For Prez!!!!

A couple more write-ups like these and Hanes and Chiltons will be out of business.

Awesome write up! Now I'm gonna have to tackle this job as my front trans case seal is leaking too. Thx for the info!

Great write up, very easy to follow. One thing to look out for though is most of the auto parts chains show both the front and rear out put seals as the same part number, so be sure you are getting the right one.