What’s leaking near my diff?

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Noticed a slight puddle after parking today and realized this leak. What is this and how do I approach fixing it?

 

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Upon inspection of the leaking fluid I’m pretty certain it’s diff fluid. It looks like maybe that hose is cracked. Can’t figure out where it’s running to though.

 

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Anyone know what size that hose is? I’ve learned it’s a pressure vent to nowhere. So it just needs replacing I assume.

 

[blert]

Yup, t'is just a breather hose. Just trim an inch off the end and shove it back on. Unless the whole length is cracked up, then take it to a local part shop and ask them to match the inside diameter.
Been through any deep water? If so, it is time to crack that pumpkin open and replace the oil. Might want to do it anyway considering the age of these trucks.

edit: words

 

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Where would the refill plug be? I haven’t found it but wanted to do it for a while now.

 

[blert]

Crawl under the driver's side of the truck in front of the rear wheel. Look at the differential, you can't miss it. Make sure to check that you can loosen it before you crack the seal on the pumpkin, you want to be sure you can fill it back up after you drain it.

 

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Is that it? Seems pretty low.

 

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Also, what kinda fluid did you use? Brand and all. I read your earlier thread but am still a little uncertain as to what to use. I can buy a gasket at my local auto store, but what’s the best way to go about changing the fluid? I should note that my current fluid does look milky. Once I crack the pumpkin, what’s the best way to ensure this is the last time for a while?

 

[blert]

That looks like it, yup.

Procedure would be something like...
- Make sure you can loosen the fill plug.
- Put big pan under the diff.
- Loosen all the cover bolts a bit.
- Pry one of the bottom corners of the cover slightly and let it drain.
- Finish removing the bolts and cover.
- Clean off all old gasket material from diff and cover.
- Use clean, lint-free rags to wipe out the inside a bit.
- Cover the diff with a clean rag so nothing gets in there.
- Remove the fill plug and inspect for metal shavings (it is magnetic).
- Prep your gasket.
- Reassemble.
- Fill.

As far a gaskets... There are many opinions: paper gasket only, silicone make-a-gasket, paper gasket with light silicone. I used a LubeLocker reusable because it was relatively cheap and I plan on doing it again this summer so it works out in time spent cleaning and buying a new gasket.

Oil would be dependant on if you diff is limited slip or not. There should be a metal tag attached to one of the cover bolts with info stamped on it.

 

[blert]

I think it's 75w90 for an open diff and 75w140(plus additive) for limited slip. Not sure if you should use the heavier option if you do a lot of towing. I use Mobil1 75w90LS in my open diff.

 

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Great info! I’ll put it to use next weekend and let you know how it goes! Thanks!

 

[curtis james]

as blert mentioned the proper way for complete change in rear diff, depending on miles i would consider just removing oil fill, the one pictured, and you can get the pump that goes on gear oil and put a long tube which normally comes with it and pump old oil out and inspect it for milky if water got into breather inlet or metal pieces, if so open pumpkin and clean if not just add new gear oil as blert mentioned and fill until its pouring out of fill and drive and recheck level. not knocking your ability on job but if ya were not sure about rear diff fill location or breather hose, ya might consider not doing removal procedure if not needed, if ya strip a bolt or warp it ya might being leaking a ton more and doing a ton more work.

 

[blert]

That's a good idea Curtis. I always forget about being able to just pump it out and refill it. Especially handy if it has been sealed up with silicone and it's not leaking. That being said, IMO, everyone should take the time and do the whole deal at least once. It is a good learning experience, it is not hard, and so long as you take a bit of care and use a good torque wrench (tighten in pattern) it is hard to mess up.

 

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I’ve got plenty of experience working on this thing! From the front wheel bearings and rotors to body mounts to fuel pump. I enjoy it. Lol. I appreciate the shortcut though, but it probably needs a good inspection. 210k probably on the original fluid.

 

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So I went and checked my manual to see how much oil I’d need and it looks like the weight is the same regardless of the type of diff. Am I missing something here? Mine is an open diff after more research thanks to y’all’s tips.

 

[blert]

Is yours a 4wd?
I think those are the specs for a 4wd. Fairly sure 2wd is 75w90.

 

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Mine is RWD. 2005 XLT 8.8 inch ten bolt diff.

 

[blert]

There ya go then. Go with what the book tells you I would suppose. 75w90 will be thinner at higher temps than 75w140.

Here's what my book says...


Either way it's not going to hurt anything but may cost you a fraction of a mpg going thicker.

 

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How weird! Okay, thanks for the advice! I’ll let you know how it goes!

 

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So I replaced fluid and gasket (it definitely needed it) and it’s been three days and noticed a leak. I believe it’s the pinion seal, I’ve seen some videos but would like y’all’s affirmation. Is this a job one could do at home or should a shop do it?