Leaking axle seal or brake caliper?

[armoredpig]

Hello friends, I recently discovered this greasy substance on my passenger side rear hub. I can't tell if it's the dreaded axle seal leak or a brake fluid leak. The caliper pin boot doesn't look right.

I checked my diff fluid and thankfully, it was not low at all. I plan to check the brake fluid today after work (I have dot4 LV arriving today).

In the last picture, I've cleaned it off as best as I can. Going to to watch it to see exactly where it's leaking from.

What do you guys think it is? Should I replace both the axle assembly (comes with new seals) and the rear caliper?

I'm also of the mind to do my rotors and pads because I get a slight shake on braking that I think is related to this.

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[airline tech]

I am going with brake fluid leak from the hose attachment point on the caliper.
Using the posted pics.

Check for security of the bolt, it may be backed off a thread, plus there are 2ea crush washers.
1 under the bolt head and 1 under the hose (block)
The washers are available at any auto parts store.

 

[Blue Streak]

Hear is what my drivers side looked like when I noticed it leaking. I would say seal unless brake line has been messed with. No guarantee on assumption.

 

[5thranger]

I am going with brake fluid leak from the hose attachment point on the caliper.
Using the posted pics.

Check for security of the bolt, it may be backed off a thread, plus there are 2ea crush washers.
1 under the bolt head and 1 under the hose (block)
The washers are available at any auto parts store.

Agree there are two brass washers looks like the leak is there.

 

[airline tech]

Then again - the pic is deceiving, as I forgot the calipers mount to the rear of the rotor.
So, the first pic is taken looking aft - (not forward)
With that in mind - Axle Seal leaking and flowing back (AFT) via airflow across it.

 

[armoredpig]

Hear is what my drivers side looked like when I noticed it leaking. I

Then again - the pic is deceiving, as I forgot the calipers mount to the rear of the rotor.
So, the first pic is taken looking aft - (not forward)
With that in mind - Axle Seal leaking and flowing back (AFT) via airflow across it.

That is a good point. I hadn't thought of that.

I am of the mind to change the caliper along with the axle assembly to rule out both possibilities. The caliper pin boot really shouldn't be squashed like that. Makes me wonder if the caliper is also seized by coincidence ?‍

 

[airline tech]

I think the boot is only deformed damaged from the (80/90) Gear Oil and it is swelling (deforming) the boot. (Rubber) taking away its natural shape (bellows).

Visually the guide pins are the same length, and the caliper appears to be (even) Top & Bottom, for the boot to be compressed that much (with a sticking) slider, you should be able to visually see it being lopsided or a shorter distance (space) on the bottom side vs the top side.
So, it appears it's only the boot itself (visually) compressed

It's the Petroleum Base in the Gear Oil that is causing it.

I did not even notice the boot, until you pointed it out with the last post.

 

[Andrew27]

This was an axle seal leak on my father in law’s 2023 with about 6,000 miles. The axle/seal was replaced under warranty. Up close it had that unique gear oil smell lol.

 

[airline tech]

That is true, there are 2 fluids that have a unique smell and will not come out of your clothes without a ton of vinegar and they are 80 / 90 gear oil and jet fuel they both have a overpowering odor.

80 / 90 gear oil is stronger though.

 

[That_one_Ranger]

I’ve lost 2 rear axle seals so far and a rear axle shaft they make you buy the whole assembly when you mess the seal up

 

[carnut122]

Clean thoroughly with the last step being brake cleaner. When all clean and dry apply this: https://www.ebay.com/itm/1765924935...MIo5OEr9TyiQMVJzbUAR0srQhxEAQYCCABEgIkU_D_BwE to the entire area. Then drive for about 10 miles and reinspect.

 

[Dereku]

Axle seal is my guess. I have done a few over the years. Hopefully they sell just a seal and not an entire axle. Rockauto is your friend.

 

[Cabose-1]

Yep just smell it. If it washes super easy with just water brake fluid. If it doesn't, gear oil. Get some on your finger how does it smell??

 

[Grandaccess]

check the fluid tank see if its low, if not gear oil

 

[armoredpig]

Yep just smell it. If it washes super easy with just water brake fluid. If it doesn't, gear oil. Get some on your finger how does it smell??

Smells like gear oil and my break fluid res is not low at all. Went ahead and ordered a new axle shaft assembly along with pads and rotors front and rear.

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