Hey everyone,

I got home late last night and smelled burning oil. Crawled under the truck and it's almost definitely the passenger side diff axle seal up front.

I've been reading about it and some people say it can leak due to debris being stuck in there? Is this true? I was on a dirt/gravel road this weekend and it was raining and kinda muddy. I looked at the breather this morning and it's still clean, but that's about as far into checking it as I got.

Any chance I can try cleaning it out with brake cleaner or would this cause more damage than good? The thing is since I was out there I drove 350 miles home and it started leaking somewhere along the way I guess. It wasn't leaking enough for me to notice at least when I changed out my front sway bar links sunday before I left. I feel like the damage has been done...

Toyota wants $555 to replace that seal that costs $26. What all tools would I need to do this myself? I have normal sized sockets and rachets, wrenches. I know I'd need a 35 or 36 mm socket for the axle nut. Not sure which size so I'll just get both. And a pry bar to get the CV out, and something to pull the old seal out with. Any suggestions for that? I have a fancy little seal puller that I used on the crank seal, but I don't have that with me here either...

Should I just replace my passenger CV while it's out as well since it's been seeping around the inner boot since I lifted it?

How long would this take as a rough guess? I've never pulled a CV, but I have changed my TREs, LBJs, suspension, timing belt, rear axle seals, etc. Any tips for doing this are appreciated.

Sorry for the long post with probably horrible grammar. T4R is blocked at work so I'm posting from my phone.

I'll try and upload some pics if I can figure out how to from my phone.

When mine was leaking it wasn't flinging stuff all over like that...but mine was a small leak. It seems like a lot still....did you recently fill your front diff?? I won't claim to be an expert.

I threw in some pics so you can see what you're working with...not sure how stuff would cause that to leak unless it got between seal and shaft or damaged seal...again, no expert.

I threw the new seal in the deep freeze (gives you a few seconds of smaller diameter, making it easier to put in) while I was pulling the cv and the old seal. The most annoying part was that there's no stop, you're supposed to put the seal in at just the right spot. Somebody correct me....I think it was something like 5.5 mm inset...and nice and even. I used the dust shield off the cv because that had a lip on it that was pretty close to what I wanted, and it worked pretty good. Certainly do some research, I've only done one seal.

When it's time to put the lower ball joint bolts back in you can drop the upper a-arm by loosening the single long bolt that runs through the a-arm bushings. Just make darned sure you don't forget to retighten it after the wheel's back on and the truck is back on the ground.

I can say when you put your cv back in be careful not to knock into the seal!
Personal experience would have me reboot the existing cv shaft if it's in good shape. I'd also check for grooves in the old boots made by the lobes rubbing each other and, if present, do a boot stretch.

Right side of the front diff where the axle goes in

seal removed

and cleaned up a little

new seal installed.


Torque wrench. Lock tite for the lower ball joint bolts, 35ish mm socket for the axle nut. Bungee or something to hold the spindle out of the way. Some sort of pry bar. I like a bfh for the pry bar because I am not strong. Something to hold the truck up and something to take the wheel off. I use a screw driver to carefully pry off the dust cover over the axle nut. Always be aware of that seal.

CV axle nut torque 174 ft lb, 4 Lower ball joint bolts 59 ft lb

Thank you for the response Habenero. I haven't touched the diff in over 10k miles so I don't know what caused it to leak like this.

You are right on the 5.5mm inset. I plan to rent a seal driver set from an auto parts store to put the new one in.

Is it a solid noticeable sound/feeling when the new CV is seated properly in the diff?

Also, what all parts will I have to transfer from my old CV to my new one? I bought the new MaxDrive Napa one, I'm just wondering if it needs to have the dust shield, snap ring, and outer dust seal that goes by the hub or not since it's new?

If the snap ring does need to be transferred is it actually easy to get off with a small screwdriver? I've never had much luck with snap rings...

Sometimes the dust shield needs to be moved over, that's very easy. Usually everything else is there. I haven't had to do any where the clip needs to be moved over. Pay attention to the gap between cv and diff before you pull yours out- it's fairly small. The new one should also have a very small gap- not a big one- that's one clue, and the tulip won't tug right out. I'm trying to remember which direction you want the gap in the clip to be when popping it in there, I believe it's at the top. Some grease on the splines wouldn't hurt. I never hear them pop in over the sounds I'm making getting them in.

Are you sure its the diff that leaking? As habanero said her leak was small and all the ones I have ever dealt with except one were small.

Did you check the fluid level?

If the CVs are Toyota they are a 35mmm, for all the times I have used replacements I have just reused the OEM nut.

If you need tools just go to the Harbor Freight off Mills Ave (16) near the hospital.

Good to know that the clip will still be there. I think you're right about it being upward. I'll take note of the gap. I think I'm gonna pull my skids sometime this week so I'm a little bit ahead of the game when it comes time to do it. I've got a whole bunch of little stuff in my advance auto shopping cart right now since they always have the good coupons. I'm sure there will be some noises/words coming out of my mouth in the process too as always when working on cars haha

How long did it take you to do the job? And what did you use to pull the old seal out and drive the new one in if I may ask?

It's definitley gear oil, it had that kinda clear not dark color that gear oil has unlike all the other fluids up there like the motor oil, and transmission fluid (power steering in mine is ATF as well). It had that gear oil smell too.

What was the one that you dealt with that wasn't small like? Was there oil run all the way down the truck kinda like mine? I'm sure mine was slightly exaggerated from the 5 hours of 70 MPH that I had just driven too.

I haven't checked the fluid level, but I can't think of what else it would be. I'm thinking I may have had a slow leak there that wouldn't drip or sling like it is now, and I didn't notice until now because of my aftermarket skids.

I'm making a trip to harbor freight tomorrow for wire brushes, pry bars, a bigger hammer, and some screwdrivers. I think I should have everything else.

I prolly used one of my seal pullers...or being a pretty big opening....anything I could get in there without scratching the axle housing. Had a new one so I really wasn't worried about bending it.

Mebbe an hour? I didn't really time it because there's always stopping to run the household and rule the kid. The seal is annoying. Once you get the truck up and the wheel off the hardest part for me is talking the axle into coming out- and going in and that's just a little patience. What time it will take you depends on what you run into.

I'm still not convinced that the seal is leaking either. Well, you'll know better than the rest of us on that one. I can't remember ever a front diff breather (left inner fender, near the bottom of it) that's clogged. Have you stuck a bit of cardboard or something under there, see if you can find the main area for the drips? My leak crept around a little (first pic), but didn't fling like that. Yours really got far down the frame, whatever it is. I guess part of that could be from the a/c? IF it's not the seal leave it alone, it's an obnoxious little bugger.

Agreed- Advance Auto Parts has some nice savings if you're careful about what you buy. TRT30 or TRT41 and I shop using Ebates for another 6%.

Just a heads up, saw a similar thread not so long ago, guy though it was his diff leaking, ended up being something else which I do not remember.

Do the oil really STINK when you put some in your hand?

And do not forget that gear oil and automatic transmission oil smell pretty similar (IMO at least)

If you think it only took you an hour or so that's not bad at all. I was figuring like 8 hours for me because Toyota quoted 4 hours of labor. I checked the breather earlier and it still moves very freely and is spotless.

I'm almost certain it's not the A/C I looked all around the compressor and didn't see any wet spots or anything and I just tested and it blows cold with no strange noises or anything. I haven't put any cardboard under it, but I did smell the fresh drips last night that were on the frame and it did smell like gear oil. It wasn't red like ATF would be either.

I'm open to suggestions on what else it could be though, I'm not an expert on any of this by any means and I'd hate to do the work in vain. I just can't think of anything else there that could leak like that there.

I'm thinking it ran down the frame the way it did because of how the CV's turn when going forwards it would throw the grease back and up therefore allowing it to run down the exhaust and cat as well as the frame like it did in my pictures. I'm thinking tomorrow I may pull my skids and check the fluid level, but I don't know if it's leaked enough to notice a difference in the fluid level yet.

If it takes you more than a couple of hours something's not going as planned, I'm thinking. Not sure what-all they were going to do for 4 hours. Spend a half hour working and 3 1/2 having a few beers? Probably they were quoting for more than just a single cv shaft and seal?

I meant run-off from the a/c being that which is on your sway bar bushing and back on the frame? That wouldn't be oily, though. I've got a valve cover leak on the back side that's leaving a bit of mess, but then it wouldn't be up on the tulip. Am curious to see what you find.

The exception was when a 98 Dodge Ram front axle leaked so bad due to the gear sheering off from its axle (no CVs used) essentially pushing the fluid out. But there had been a leak for some time beforehand (I think close to a year and that was slow).

Get yourself at least one 2lb orange deadblow hammer at HF.

Look closely at the power steering fluid level as well.

It was definitely oily, you can smell it burning too after driving. I'm about 99% that it's that seal. The skids have a good bit of oil slung right under the CV and behind it with nothing in front, or above the CV either.

It's actually very similar to how my passenger side rear axle started leaking. Fine one day, walked out another day to a literal puddle around my rear tire. Not the slow leak like most people start with. It was so fast it didn't even get to the shoes haha

I have no idea what they were quoting for but I'm gonna do this myself. so far I'm a little over $200 into it for a new CV and seal and a bunch of tools I didn't have before. I'm shooting for 4 hours or less myself after reading through this stuff multiple times. Mine will be a little more complicated because I have to pull my spacers, clean the threads, and then reinstall, and I have to pull my shrockworks skids to top off the diff afterwards and they're kinda a pain. Other than that it actually doesn't look bad. Wheel off, sway bar link, dust cover, axle nut, 4 LBJ bolts, pry axle out, pry old seal out, seat new seal, new axle, reinstall everything, top off diff. Test drive!


I haven't checked the PS level, but I will just to make sure. Doubt it's that though since I have ATF in mine also.

I picked up my new CV from Napa today, pry bars, screwdrivers, seal puller, 2.5 lb dead blow hammer, wire brushes, hex sockets, punch and chisel set, pretty much anything I could possibly need. I rented a 250 ftlbs torque wrench and seal driver set. Both brand new! I should have everything now to do the job. I'm gonna get off early Friday, hopefully get it knocked out in a couple hours and then if the weather is still good I hope we can still make it out for a little camping/wheeling.

good, keep us updated about this we are pretty curious