Overfilled Rear Diff Fluid? Or Bad Rear Seals?

[scshack]

I recently drained and refilled my rear diff in my 2002 3rd gen. I do not have the greatest area to work from, so when refilling the rear diff, the vehicle was facing uphill (the rear diff was downhill). I filled it up until gear oil started flowing out of the fill hole, but squeeze a bit more in since it was facing downhill. I took out my 4runner this past weekend for the first time and put around 200 miles on it. Everything seemed fine and running smoothly.

However, a few days after it's been parked, I noticed gear oil leaking from the driver's side rear tire.

My question is, are the rear seals leaking because of a possible over-fill of the rear diff, or does my rear diff fluid exchange have nothing to do with it?

If it's just because I over-filled the rear diff, then parking on level ground and removing some of the fluid should solve my issue. Unless I've caused more damage to the seals with the leaked fluid. It's hardly any amount of fluid as you can see in the picture.

If this is just a coincidence, and my seals just happen to go bad and started leaking, then I need to look into replacing the rear seals and bearings, which I am hoping is not the case.

Let me know everyone's thoughts.

EDIT: I warmed up the vehicle and parked in on level ground. When I pulled the fill plug, no fluid came out. I filled up the rear diff fill until fluid was barely, just barely dripping out. I cleaned up the area around the rear seal on the tire, and will sell if any more leaking happens.

 

[jross20]

By chance were you able to tell if it was low when you first drained it? I'm not 100% sure on the rear axle seals, but I wonder if it's possible that when it's full it leaks but then it leaks down to a certain point and then stops.

When you opened up the axle did she hiss at all? (As in, was the rear axle under pressure)

 

[scshack]

I am pretty certain it was not low when draining it. I just drained out all the fluid, at least 2.5-3 quarts. Which is what my Rear diff 4WD w/ locker FSM states for capacity (2.9 quarts).

The axel DID NOT hiss when I opened up the rear diff fill or drain plug. So rear diff was not under any pressure.

 

[JohnMc]

It shouldn't build up much pressure with a plugged breather, simply because the axle seals won't hold much, the air will push on out through them, and take some oil with it.

I'd first check the condition of the breather - it's on the top of the pumpkin, on the left side of it. It's a little 'jiggle valve'. Quickest check is to just see if the metal cap on top of it can jiggle around. If so, it's probably not stuck? But it might be worth the effort to take it off and check.

If that is NOT stuck, then you are going to need to replace the axle seals, and almost certainly replace the brake shoes as well. Soaking them in oil is not good. Possibly the rear bearings as well. But unlike some vehicles, these are sealed, so it's not as easy for an oil leak to wash out the grease and ruin them. But if you're up there in miles (like... 200k+) it might be a good idea to go ahead and replace them jsut for peace of mind?

 

[octanejunkie]

I have never seen a leak like that, it's almost like the seal is gone. Usually a little bit seeps out and gets flung around the outside of the wheel, in a radiating pattern. Your pic looks like an actual leak.

Are you sure it's gear oil?
Checked your MC level lately?

Sent from my Pixel 4 XL using Tapatalk

 

[scshack]

I have never seen a leak like that, it's almost like the seal is gone. Usually a little bit seeps out and gets flung around the outside of the wheel, in a radiating pattern. Your pic looks like an actual leak.

Are you sure it's gear oil?
Checked your MC level lately?

Sent from my Pixel 4 XL using Tapatalk

I am not 100% sure it's gear oil (I was making an assumption based on visual evidence). It's not sprayed radially like other leaking seals, so I'm wondering if it started leaking after driving and parking it. I only drive it on the weekends, sometimes every-other-weekend.

I checked the master cylinder and it's full. I recently bleed the brakes and cleared out the old fluid and replaced it with new fluid. It's plenty full.

 

[scshack]

It shouldn't build up much pressure with a plugged breather, simply because the axle seals won't hold much, the air will push on out through them, and take some oil with it.

I'd first check the condition of the breather - it's on the top of the pumpkin, on the left side of it. It's a little 'jiggle valve'. Quickest check is to just see if the metal cap on top of it can jiggle around. If so, it's probably not stuck? But it might be worth the effort to take it off and check.

If that is NOT stuck, then you are going to need to replace the axle seals, and almost certainly replace the brake shoes as well. Soaking them in oil is not good. Possibly the rear bearings as well. But unlike some vehicles, these are sealed, so it's not as easy for an oil leak to wash out the grease and ruin them. But if you're up there in miles (like... 200k+) it might be a good idea to go ahead and replace them jsut for peace of mind?

The breather is able to move and is NOT stuck. I didn't take it off, just moved it around with my hand, and it's freely spins and moves.

This "leaking" issue has made me start to think about the possibility of getting new seals, bearings, and drum brakes. Not sure when the last time it was done (only had the vehicle for 20K miles). I may just monitor it , and if it's still shows signs of leaking, I'll replace it all.

 

[19963.4lsr5]

Gear oil has a very specific smell……


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[Jakeepoo3]

Gear oil has a very specific smell……


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And viscosity

 

[Mighty Buffalo]

Looks exactly like when my axle was leaking, except mine was passenger side.

 

[Bad Luck]

Looks like an axle seal leak to me. Put the rear axle on jack stands, remove the wheel speed sensor, and spin the wheel/axle shaft while looking at the tone ring through the wheel speed sensor hole. If it’s wet then your rear axle seal is leaking beyond any doubt.

 

[nissanh]

The cap of the breather will move freely. The mating surface may have the flapper suck closed. The setup in the breather is the main body, flapper, spring and then the cap. You can pry open the cap (watch for the spring), clean the flapper and reinstall the cap.

 

[jross20]

The breather is able to move and is NOT stuck. I didn't take it off, just moved it around with my hand, and it's freely spins and moves.

This "leaking" issue has made me start to think about the possibility of getting new seals, bearings, and drum brakes. Not sure when the last time it was done (only had the vehicle for 20K miles). I may just monitor it , and if it's still shows signs of leaking, I'll replace it all.

Shit, you just reminded me that I need to change my drums...

But anyway yeah I've been thinking about the rear seals and bearings as well. It seems like a fairly easy job except I am not good at bleeding brakes... So that part I'm not so sure about.

 

[3bears]

Shit, you just reminded me that I need to change my drums...

But anyway yeah I've been thinking about the rear seals and bearings as well. It seems like a fairly easy job except I am not good at bleeding brakes... So that part I'm not so sure about.

so you think changing bearings and seals seem simple but bleeding brakes is not....am i missing something here

 

[jross20]

so you think changing bearings and seals seem simple but bleeding brakes is not....am i missing something here

Let's just say the last time I tried it there were scary stopping issues... Lol.

Plus, are you supposed to use that pressure machine? I can't quite remember as it has been too long.

 

[Bad Luck]

Let's just say the last time I tried it there were scary stopping issues... Lol.

Plus, are you supposed to use that pressure machine? I can't quite remember as it has been too long.

No pressure bleeding machine required.

 

[mtbtim]

Here's two videos for you on this subject. I suggest watching both. The second video is all about introducing a new tool for the job and sharing more tips for the job. Be sure to read the video descriptions and pinned comments as well because there's important information in both areas.

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[scshack]

Here's two videos for you on this subject. I suggest watching both. The second video is all about introducing a new tool for the job and sharing more tips for the job. Be sure to read the video descriptions and pinned comments as well because there's important information in both areas.

Thanks [MENTION=120071]mtbtim[/MENTION] for your help and replying to this thread. Your videos (and Shawn’s) have been a major tool I’ve used for almost every maintenance job I’ve done on my 4Runner’s. Lower ball joints, new suspension for lift, ARB bumper install, timing belt water pump job, JBA UCA replacement, bud built rear diff cover, and now axle seal replacements. Thank you for your content and your help. I know there is major effort and work that goes into your videos, it’s truly informative and extremely helpful.

Back to the thread. I ended up replacing the drivers side rear seals, bearings, and associated parts. It was for sure a leak in the seal, there was gear oil where the seal and ABS sensor router meet up. I caught the leak soon enough, and the drum brakes were not soaked in. gear oil or showed any signs of oil around the brakes.

I took the axle and bearing to local Toyota dealership to press on the new bearings. I also asked them to use the mrcoffee method of flipping the inner bearing spacer. I also asked them to leave 3-4mm of polished axle. I didn’t perform grease test to see where seal was mating, since I’m not able to move bearing seal, I’m hoping the seal is good now. Time will tell. They charged me 1 hour of labor at $149, to remove old and press on new bearing.

I wanted to do both sides at the same time, but my area to work only allows me to work on one side at a time. I have the parts to do the other side, but I’m just holding off to monitor the newly replaced side. Just going to monitor for now. Drove it around the block and no noticeable leaks yet. I’ll post some pictures of part numbers I used for my 2002 SR5. Be sure and checkout [MENTION=120071]mtbtim[/MENTION] videos and the description for parts for 1996-2000 and 2001-2002 a few parts for the job do differ. It cost me a total of $233.76 for parts for both sides to replace all the parts listed. I purchased 3 seals just incase I damaged one. Only need 2 (one for each side).

Plus another one $8.47 for new crush washers for the real diff drain and fill plug. Here is link to crush washer set.

I did use a hammer seal puller to remove old seal as a loaner for Advanced. The Lisle 56750 Seal Puller wasn't getting the seal out easily, I didn't want to damage the axle housing. The loaner tool pulled it out with 2-3 slides. Works perfectly. I used this tool to help drive in new seal , it worked best with the 76mm head.

Hope this helps anyone else preparing to do this job.