Rear Axle Problems

I have had a problem with rear axle leaking fluid. My Tundra is 2005 double cab 2WD V8 266K miles. Every 3 years or so (since I bought the truck new in 2005), the rear axle leaks differential fluid. I'm not a mechanic so I could be using the wrong terms. I'm an excellent geophysicist, but a horrible mechanic.
First few times I would notice the leak because the axle would squeak. Then I started paying attention and would see oil on drivers rear tire and breaks. I have replaced seals about 5 or 6 times through the years (about every 3 years or so). Finally a mechanic noticed an imperfection on the axle, which he thought might of caused stress breaking the seal, leading to the leak. So 12 months ago we replaced the axle on that side. Thought the problem was fixed, but no. Just after warranty expired we noticed leaking oil again.

So now I'm thinking have to replace the entire rear end. Is this the next step as far as you guys think? Now is not the time to be buying these kinds of parts - looking at nearly $2000 (still have to poke around) + labor. Junkyards barely have any parts anymore. Not even sure if a mechanic can really diagnose this properly without taking the differential apart - could there be another answer besides replacing the entire rear end? Looks like about $400 or to really look into the differential, and don't want to spend that unless I'm ready to just replace the entire rear end.

Advice?

 

have you verified the breather on top of the pumpkin is free? if that breather isn't functioning correctly, you'll keep blowing axle seals as the housing heats up, causing pressure to build. they're the weakest link so they go out first.

 

Yup, this^^

If the diff has no way to vent/offgas through the breather, it has to find somewhere else to go. Guess where the easiest spot is? Axle seals.

You should fire your mechanic if they missed this, it's a total no-brainer. I would replace it proactively if never done, especially if you're in a rust-belt state.

You can find the breather, try pushing it down, does it move up/down or is it frozen?

 

No one had ever mentioned that, and I've had multiple mechanics over the years work on this. In fact, going through old paper work I learned that I've replaced the left axle twice over the years. Didn't even realize that. Is the breather just for 4WD? Everything I lookup up only reference 4WD (mine is 2wd). But I also know I've been driving across low water crossings in that truck for 15 years - maybe this starts to make more sense? Thanks for any info.

 

Try this first. If they're still leaking look here:

https://www.tundras.com/threads/rear-axle-seals-bearings.39306/

Post #102 is where I finally got it right. You'll need a special tool for the axle, and a new bearing kit/seals. Timmy the tool man has a video you will need to follow 100% to get this right.

https://youtube.com/watch?v=AVhSDnw2ugo&si=EnSIkaIECMiOmarE


Also, @tvpierce has done this and can add anything I missed.

 

Depending on how long it's leaked, he might get away with just replacing the inner seals like i did. no need to mess with the tone ring, bearings, backing plate, or any of it.

 

Only thing I'll add is that Timmy did a second video using an updated tool that's less expensive, easier to use, and makes the need for a separate bearing puller unnecessary.

Here's the updated video:

 

Here's where the breather should be if you've got one, OP, and this is what it looks like. It should push in/out freely, but it can get jammed up internally while still moving. You should replace it if you're blowing out seals. If you find it, let us know, can give part number if you need it.

 

And if I remember correctly, the cap (the part that looks white in the first pic) should be able to spin.

 

Not sure about others, but I even went so far as running a fuel line that attaches to the breather, up into my brake light to prevent gunk from getting into it. After replacing the seal on one side of my rear axle 6 months into owning my truck by myself, then after more leakage 5 months later I paid an axle shop(650$ for one side), I really did not want to do it again. If you read into it you'll see this is only "really needed" for people doing water crossings or going into serious mud, but after washing my car even after a little rain it's surprising to see how much shiza gets splattered all up on that breather and the axle itself. Better safe than sorry or maybe I am just obsessive

 

You guys are a little bit beyond awesome. Great information. I'm a little handicapped in that I can't lay down to get under the truck to check things. Gotta wait for the boy to get home and check it out for me. Do all trucks come with the breather? I have a 2WD truck and not sure if it has one (will find out of course when kid gets home). We have a low water crossing on country property that I definitely have been crossing with up to about 18" of water a few times a year for the lifetime of the truck. Will keep y'all appraised of what I figure out. Thanks!

 

OP says Squeak and Oil on rear tire and brake ...

Not a mechanic here but is there a path for the rear differential fluid to leak over the brake and tire? Asking because some suggested the rear diff breather valve solution. basically my own curiosity now.

Breather valve potential issues or not maybe a separate thing but can the rear diff fluid make it to the tires and brakes? I didn't think there was a path. Is the rear axle solid or hollow? I can see at least a better "path" if hollow and some internal passage through seals, etc.

 

I'd assume you have a breather, but make the boy earn his keep

Yes, the path of least resistance ends up being the seals near the wheel. There is an inner axle seal and outer axle seal.

My inner axle seal went out completely and puked out hot gear oil while I was driving. Completely soaked my brake shoes and wheel. Also shot a wheel bearing.

My breather was full of crud when it happened and I had not done the relocation.







Oily drum vs unaffected drum:




Here's what the axle tube looks like:







This is my breather extension line, I had to use this part # from Toyota:

$7 90404-51319 Toyota Genuine Parts - Union (90404-51319)

90404-51319

 

good to know!

Just to be clear, you are suggesting that the rear differential fluid from the "pumpkin" can leak through the seals (more than 1) and make it to the tire/brake area ... So basically there is an internal path i.e. Hollow rear axle plus seal failures to provide the internal path.
btw, not arguing with you. Just trying to make sure I understand the design.

 

Exactly, the tube is hollow other than the axle shafts, and there's gear oil inside from wheel to wheel. The inner axle seal keeps the oil from leaking out under normal operation.

I don't think it's super common for both axle seals to blow at once though. The other two points the gear oil can easily go if the breather is clogged are the differential gasket or the pinion seal.

 

Is this oil (I highlighted above) same as rear diff oil/fluid? Meaning when we change the rear diff fluid, are we also changing this oil? Or is this oil part of another sealed (axle shaft?) unit that is supposedly a "lifetime" oil?

 

Yes, it's the same as your gear oil in the differential. Most of the oil is at the differential, just some of it make its way up the tubes.

 

Thanks for the info!

I have another 4-WD car with a CV Rear Axle ... much different design than the Tundra heavy-duty solid axle.