Fluid leak above rear diff

I have some kind of fluid leak above the rear differential. My initial thought was brake fluid or diff fluid since there are brake lines and a differential there. However, after getting under the truck and poking around it looks like it could be fuel vapor related? it seems like everything in this area of the truck has a layer of oily buildup on it even the area above the spare tire is saturated.

I checked the brake fluid level and it is right where it should be and I don't have any warning lights or anything. The truck runs fine brakes are good, the only symptom is 'shit wtf is leaking back here'. I prefer to do as much of the work on my truck as possible but I'm not familiar with the fuel vapor system if it is in fact the problem.

Any thoughts / recommendations before bringing it in to have someone else look at it?

 

Kinda looks like someone (or the dealer) rust proofed up in there?
If not, a smell or taste test of the fluid should tell you if it’s gas or brake fluid....

 

Gonna have to smell it.
Looks like rustproofing.

 

Welcome to the forum, like the others have said looks like some kind of protective coating. What does it smell like? Does it wipe off easily? New or used? Inquiring minds want to know.

 

I’m not sure where the breather vent is, but I think if overfilled the diff puke some gear oil out,,, that’s just a stab. I agree w an undercoating.

 

Doesn't look like a breather vent mod has been added. In his picture the current vent is the little round silver thingy on top the diff body straight up from the "R" in the armor plate cover, just under the wire. Junk should only be on the diff if extra came out there. I also agree on some frame coating as if it was oil blown out somewhere else it probably would have covered the tire? Not just show where it touched the frame.

Or did something being carried on top the bed leak and creep along after going through the drain holes?

Either way, if it's oily it's extra rust protection!

 

I'm wondering if there is UV leak dye that could go in gasoline.

That would probably help you find the leak.

 

I have a 2023 Tacoma and do all of my own service. I noticed this past service that my is covered with what looks like brake fluid?? My reservoir is a bit low but I cannot find a point of leakage??

 

I ended up taking it to the dealer. They diagnosed a leaking rear diff pinion seal. Quote was ~900 to fix. I had them top off the diff and took it home. Replacing the seal myself for less than 100 dollars.

 

Make sure the vent isn’t blocked.