Transfer case leak at front driveshaft?

[anhizer]

I noticed some drops of oil under the truck today and took a peek and found some gear oil (slight greenish tinge, smells vaguely of sulfur). I looked around and found what i think is the leak. There is some oil near the flange on the front driveshaft output. I looked at the fill and drain plug and those appear to be clean; there is some oil around in other places nearby but they are fairly dry compared to the output shaft. Anyone want to confirm my suspicions here?

First image is looking under the truck from the passenger side; right side of the photo is towards front of vehicle.
Second image is from the rear of the vehicle looking forward. Right side of image is the passenger side (camera is held above the cross member).

I did do a little water crossing recently (at the beginning of the covid lock down, less than 1' at a offroad park) which splashed some dirt around which could have caused the issue. I haven't driven the vehicle much but put about 60 miles on it today and noticed it. I haven't checked to see if the breather is clogged but looked at a couple of other posts and this was mentioned as a possible cause. I'll take a peek tomorrow and see what I can see there.

 

[JunkCrzr89]

Check/clear breather first. If leak persists, it does look like output shaft oil seal. To replace seal, you’ll need to remove driveshaft and front extension housing from t-case

 

[2001LC]

I'd also check the breather as @JunkCrzr89 suggest. I've yet to find one clogged.
Edited 6/18/23: 1998-02 TC breather is shared with AT. I recently found one where the shared breather tube had fluid in it. TC was leaking very badly at both end and level to high. Which with such a bad leak, one would expect TC to be low. I suspect contamination of fluid. After flushing TC fluid and adding AT-205, leaks stopped.

I've been seeing more of these front differential input shaft seal leaks lately. Interesting they've been in 1998-2000.

I think in the cases I'm working, it's age related. I'm having a lot of luck in stopping the weep/leak by; changing the gear lube to Mobil 1 75W-90 which is a synthetic and adding ~2.4 oz of AT-205. A note: One differential gear repair shop stated, "do not use synthetic gear lube". But they do give and exception for Mobil 1 gear lube.

After driving more than 5 hours, I clean the area. Then watch for leak to reappear. Knock on wood, one I did like this 2 years ago is still holding tight.

If leak still present, I would replace the seal. But I've yet to replace the input seal, as the AT-205 has been working. If I do replace one, I'll be looking into setting back lash or preload (I do recall which term is correct). I say this because, a post by Slee I saw from many years ago.

 

[anhizer]

I finally had a chance to climb under the truck and check the vents and they seem clear to me (nothing obvious at least). I poked a wire through as far as i could easily and didn't feel any obstructions. I called a couple of shops locally and the shop that is known to be land cruiser specialists quoted me $1100-1500 over the phone which seems a bit outrageous. Another shop cited the book rate at 5-6 hrs, but then no-quoted after looking into it further. I called a well reviewed transmission shop and they quoted me ~$600-700 which seems more reasonable, but that guy admitted to never working on a land cruiser before. Any thoughts on what this sort of job should cost? (PS anyone know a good transmission shop in San Jose? the $1500 quote was from a shop up in San Carlos which would be quite a drive for me).

 

[JunkCrzr89]

I finally had a chance to climb under the truck and check the vents and they seem clear to me (nothing obvious at least). I poked a wire through as far as i could easily and didn't feel any obstructions. I called a couple of shops locally and the shop that is known to be land cruiser specialists quoted me $1100-1500 over the phone which seems a bit outrageous. Another shop cited the book rate at 5-6 hrs, but then no-quoted after looking into it further. I called a well reviewed transmission shop and they quoted me ~$600-700 which seems more reasonable, but that guy admitted to never working on a land cruiser before. Any thoughts on what this sort of job should cost? (PS anyone know a good transmission shop in San Jose? the $1500 quote was from a shop up in San Carlos which would be quite a drive for me).

IMO, it’s a 3-hour job max to replace a $10 seal, and that’s with beer breaks. You don’t need a transmission shop.

 

[Euan Palmer]

I just did it myself and as a novice, I could say the that the job is relatively easy the hardest part was getting the transfer case back up into the truck.

 

[anhizer]

Thanks for the updates- I know i could probably do it but would need to buy some tools (gear puller and press) from what i understand. I found another shop nearby that quoted $700 to replace all the seals (front, rear, input, and one other) so ill probably just have them do the work. I have small kids and have been super busy at work so seems like a good job to farm out. Thanks for the responses everyone!

 

[abuck99]

So before you spend the $$$- try adding AT205 reseal to the TC and see if it helps. Worst case your out $13, but the upshot is substantial.

Google Search

 

[JunkCrzr89]

So before you spend the $$$- try adding AT205 reseal to the TC and see if it helps. Worst case your out $13, but the upshot is substantial.

Google Search

Agreed. @2001LC suggested this too

 

[JustJay]

Jumping on this older thread but it's exactly what I'm up against. I'm in the midst of restoring my 72' 40 and have found a leak in this exact same spot. Installed OME lift a few weekends ago and noticed a pretty significant leak shortly after. Think small puddle where there was none before. I wonder if I somehow cranked on the front end driveshaft when I was reseating the U-bolts.?. Anyway, hoping that your AT205 suggestion will work as I'd really rather not get into dropping the transfer case. Sounds like I should flush the trans fluid and then fill with AT205. Maybe a stupid question but my rig isn't mobile just yet so will this do me any good or does it need to be able to cycle the fluid through?

Final question - If the AT205 doesn't work, am I correct in understanding that I'd have to drop the TC to fix leak or could I get at it from just the driveshaft side?

 

[2001LC]

Jumping on this older thread but it's exactly what I'm up against. I'm in the midst of restoring my 72' 40 and have found a leak in this exact same spot. Installed OME lift a few weekends ago and noticed a pretty significant leak shortly after. Think small puddle where there was none before. I wonder if I somehow cranked on the front end driveshaft when I was reseating the U-bolts.?. Anyway, hoping that your AT205 suggestion will work as I'd really rather not get into dropping the transfer case. Sounds like I should flush the trans fluid and then fill with AT205. Maybe a stupid question but my rig isn't mobile just yet so will this do me any good or does it need to be able to cycle the fluid through?

Final question - If the AT205 doesn't work, am I correct in understanding that I'd have to drop the TC to fix leak or could I get at it from just the driveshaft side?View attachment 3365635

You must drive after adding AT-205, for a total 5 hours (doesn't have to be in one drive) minimum. You can just add AT-205 to your fresh fill now, the drive. But if sludge built up inside on the seals. AT-205 will have difficult time getting absorbed by rubber seals.

If TC has sludge build-up now. You can do a chemical flush, once drivable. Then drain and fill adding AT-205. Or perhaps just fill with Mobil One (synthetic oils clean) and drive a few thousand miles. The drain a fill, adding in AT-205 w/second fill.

The 100 series TC is different. So you may not get a good answer here in the 100 series tech section. But if it comes to needed reseal. You can try in place first.

 

[JustJay]

Yep, makes sense. I'll put it on the list of things to remember when I get it mobil again - ha. Thanks for pointing out that I found myself on the 100 series tech section. I guess I got so excited to see that I found someone with the same issue that I had I totally missed that I was in the wrong place! I appreciate the advice.