Black oil on wheels and clunking noise, leaking axle seal or differential?

Hey everyone I have a 2005 toyota tundra rwd v8. It has 210,000 miles and it had the differential replaced about 10 years ago. The car was originally my father and we use it as a work truck so it regularly carries 1000-2000 lbs. Now that he has retired, I am going to fix it up.

My father has a bad habit of not putting on the handbrake when parked and carrying heavy loads.

For about a year I have black fluid leaking from my wheel. When creeping the car slowly i clunking noise comes from the rear of the car, it is especially noticeable in turns. I am certain that the rear axel seal has failed and it is possible that the diff has also failed. I am going to replace this myself as I am quite mechanically inclined and I have plenty of tools.

I also have an audible whirlling noise coming from the engine bay, very noticible when accelerating at speed possible radiator fan belt failure?

My question is.
-Should I also go ahead and replace the bearings?
-Is the sound coming from the bearings or is it actually because the differential might be bad from losing all its fluid?
-anything specific that I should be aware off?

pics are attached

Thanks!

 

Looks like the rear axle seal is leaking.

https://www.tundras.com/threads/recent-axle-seal-tips-hints-and-prayers.92986/

 

thanks

Does this describe why i hear the clunking noise? could the bearings be worned?

 

Maybe. And yes, if it’s leaking diff fluid into the bearings it will wash the grease away and increase friction in the bearings.

 

Welcome to the forum. Have you read the first two replies in our community-created 1st gen thread?

Clunk-wise, the 2WD trucks have a known issue with clunks, related to the transmission crossmember getting hairline cracks and bolts falling out, more info in that thread.

That would be my 1st suspect of clunk. My 2nd suspect would be the leaf packs. There should be a 4-5mm round plastic disc/shim between each leaf, usually at both ends of the leaf. If any are missing, you'll also get a clunk in the rear.

Given the mileage and heat the truck has seen, if the 1-way vent valve on top of the diff is shot, when diff fluid heats up, and the valve is clogged or not functioning (as it may be if it hasn't been changed in 100k+ miles), wanna guess where all that build up pressure is gonna push out? Either the axle seals or maybe the pinion seal. When was the last time you replaced that stupid little $5-7 valve?

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Have you confirmed this?! Drain the diff and see the condition of the fluid and if there's metal on the plug. If this is the case, you've got much bigger problems. Sounds like you might be replacing the entire rear.

 

Wheel cylinder?

 

I thought that too, but then I noticed, the fluid seems to be passing on inside of the drum backing plate. Granted, it could still be a wheel cylinder, if it blew a seal from the inside.

I was going to tell @Atran, the real way to tell is the sniff test. Run your finger through the wetness, and smell. If it's a bad seal, that'll be some foul-ass-smelling gear oil. If the wetness doesn't smell like gear oil, there's a solid chance it's the wheel cylinder.

Of course, the best next-course-of-action is to pop the wheel off, pop the drum off, and share a picture of what's underneath. We'll probably know in about 2 seconds of seeing the pic what the exact cause is. But I get it, some people don't like popping the drums off. There's often a lip inside of the drum that grabs the shoes if you don't back off the adjuster. And if you don't re-dial-in the adjuster, your braking goes to shit.

 

And first can just pull the fill plug and check the level.