99 4RN Wet Rear Diff - Welcome advice

[Rwetmore1]

Just had my 99 runner serviced for the first time in 2 years (I live in Vancouver so it sits 90% of time).

I went to a lube place who told me my rear diff was empty?! I know they are up sell artists but that got me concerned. I had them fill it and asked if it was leaking. They said no they thought it was normal sweating/seeping.

So it's been about five days since I've been there and I got out the camera to pull some shots of my rear diff. Looks wet on the bottom. I don't really care if I have to top it up every once and while I just don't want to ruin rear end. It's working fine now, haven't had any weird hums or squealing back there so I assume it's not damaged.

What do you guys think?

 

[Victor]

Hey there,

Just looking at the picture from that angle is tough to decipher which part is leaking. If you could take a pic from the front, that'll be easier to pinpoint where she's leaking from. That being said, there's 3 possible area's for it to leak. Pinion seal, the 3rd member and the axle housing, and the drain plug.

 

[Rwetmore1]

I'll see if I can snap some pictures sometime today. I'm at work so it might be tough to get out and under it.

My main concern is the rate at which it's leaking. It doesn't look like it's dripping oil but I'd hate to have it run dry while I'm on the road before I've had a chance to fix it.

 

[Rwetmore]

So i crawled in under it all and saw there is no fluid leaking from anywhere else except that spot.

It also doesn't look like it's coming from the drain plug and I don't think it's dripping or anything. I'll put some cardboard under it tonight and see if it drips.

Is there a chance that the guys at the lube place got oil on it and it's just wet from that?

 

[ellner357]

So i crawled in under it all and saw there is no fluid leaking from anywhere else except that spot.

It also doesn't look like it's coming from the drain plug and I don't think it's dripping or anything. I'll put some cardboard under it tonight and see if it drips.

Is there a chance that the guys at the lube place got oil on it and it's just wet from that?

I'd clean it up with brake clean and keep an eye on it.

 

[Doc2012]

If they got it wet, you'd see the trail from the fill plug to the bottom.

Just how rusty is your rear axle? It looks pretty bad to me. There's a good chance it's leaking.

Try wiping that off, and see if any runs come back.

 

[Rwetmore]

It's all fairly rusted. I'll clean it up and see what happens. Seems like a weird spot to be leaking from though.

 

[ellner357]

It's all fairly rusted. I'll clean it up and see what happens. Seems like a weird spot to be leaking from though.

Problem is if it rusts through enough it can crack or split it even just become pourus or perforated. I'll cross my fingers for you.

 

[rjaudi]

Mine went right around where yours is leaking. That plate where the fill plug is located is pretty thin. I ended up getting a junkyard axle and am in the process of swapping.

 

[JohnsD90]

I would look for another axle housing but in the meantime, i heard you can clean up the area and JB weld it.

What is a likely scenario is the your diff breather is clogged which means no excess pressure from the diff can be released, which then as the pressure builds inside the housing it either starts leaking at the seals or if the housing is rusting it ends up making pinhole holes in the housing and pushes the fluid out of them to release the pressure, and even when the pressure is released the fluid will still come out until the fluid level is below the hole.

So i would hit the area with brake clean and then a wire brush, change the diff breather ($3), and then look to see if there are any pinholes in the axle housing, and if there are you can short term (potential long term) patch it with JB weld.

 

[Rwetmore]

Yea I barely drive it (just up to the hill or camping) but that being said I do having it...working.

I'll clean it up and see if it's seeping. I watched it all day and it didn't drip and the wet area didn't change. I may try the JB weld and pressure valve should it be leaking a bit.

The rest of the ax just has some surface rust (as does a lot of the undercarriage) the only flaky rust seems to be concentrated on the diff.

 

[ellner357]

Yea I barely drive it (just up to the hill or camping) but that being said I do having it...working.

I'll clean it up and see if it's seeping. I watched it all day and it didn't drip and the wet area didn't change. I may try the JB weld and pressure valve should it be leaking a bit.

The rest of the ax just has some surface rust (as does a lot of the undercarriage) the only flaky rust seems to be concentrated on the diff.

Silly question? After cleaninig it and before watching it did you drive it much on the highways?

 

[Rwetmore1]

Not a silly question. Just through the city. It wouldn't have had a chance to get a lot of pressure from heat if that's what you're thinking. 30 minutes tops.

 

[ellner357]

If it was me I'd try and get out on the highway and hit some big hills after I cleaned it. Just give it a real workout and warmup.

 

[Forrrrest]

Ewww I'm so glad I live in nor cal!!! That rust looks nasty....

 

[Rwetmore]

YEa i'm in Vancouver so I thought it was just light surface rust. I'm heading to Whistler this weekend so that should be a workout. I'll clean it up nice before I take off and see what it's like when I get there.

 

[The Deec]

I had my axle housing replaced last summer due to heavy leaking around the pumpkin going about 1 foot left and right down the housing. this picture was the leaking on a good day. Mainly due to Extreme salt belt usage up in the Allegheny Mountains. Yours does not look as bad as mine, luckily.
It was really nasty and continued forward towards the 3rd member. Still paying my dad back for covering it for me. Hopefully yours holds up!

 

[Rwetmore]

Alegheney? I used to live outside Midland PA! I know that salt belt well! YEa. It hasn't leaked this week so fingers crossed to see what it does on a trip tomorrow.

The new rear looks good. How much did that set you back if I can ask? My pumpkin doesn't seem to be in that kind of shape but I have a bad feeling that if it's pinholes that it gets there....

 

[The Deec]

It cost a bunch, just over a grand for the housing and swap over at the dealer, and then on top of than another grand for a new steering rack and power steering hard lines... the salt really got to it. Ive put about 10 grand into replacement parts and upgrades. Ready to go a few more 100k. If I didnt grenade my front diff and t case 2 years ago I would've had a nicely modified 4 runner but you pay for your mistakes when your in your early 20's and having "fun."

 

[JohnsD90]

It cost a bunch, just over a grand for the housing and swap over at the dealer, and then on top of than another grand for a new steering rack and power steering hard lines... the salt really got to it. Ive put about 10 grand into replacement parts and upgrades. Ready to go a few more 100k. If I didnt grenade my front diff and t case 2 years ago I would've had a nicely modified 4 runner but you pay for your mistakes when your in your early 20's and having "fun."

If i were you i would sell it and take a trip down to the Carolinas and find a rust free truck and transfer your mods too it and enjoy going under your truck and not having rust falling everywhere.