I replaced the breather valve in my 2011 without dropping the differential.
The part number of the breather is 90930-03235 (about $4 at the dealer).
Removal
I cut an opening in the floor under the trunk area. You need to remove the second tray piece closer to the rear seat (secured by four philips screws, two per side, the piece is held in by a couple of snap connections-just pop it up with your hands after removing the screws). The breather valve is approximately 19" from the left trim piece as shown in my photo, just right of center (about 3/4"to the right of the center line) underneath the scrunchy duct tape looking material.
Initially, I cut a round hole about 1" diameter (big enough to get a socket through). I then realized that the breather was not threaded in and I would need more room. When that wasn't big enough, I cut a rectangular flap that I could bend open to the right. I tried to get a small pry bar under the lip of the breather but no luck (and the angle was tough with the small opening).
Today, I cut a larger square flap that I could further bend open towards the rear seats. I purchased the $25 slide hammer at Harbor Freight and tried to use the square attachment that has a slot. I opened up the slot a bit with my dremel to the point that it would fit around the width of the breather under the breather lip. This also required making that opening on the slide hammer attachment taller to accommodate the movable part of the breather. However, I was still unable to get this underneath the breather lip - too little room between the lip and the diff. I think the press fit of the breather has the lip very close to the differential.
I then used the slide hammer to lift off the movable cap of the old breather. Underneath the check valve piece was all gummed up with corrosion. Even though the movable cap of my breather was free (from me messing around with it a few months ago) the check valve was not moving (no way to see this unless you break off the movable cap part of the breather).
With the breather cap removed, I then drilled out the center of the breather (first with a bit the same size as the opening in the new breather, then one size larger), stopping to remove debris from the drill bit. This got the hole larger to the point where I could now use the seal pulling hook that came with the slide hammer. I did have to make the hook a bit shorter so it would fit inside the hole in the breather, but I still left a bit of a lip on the attachment so it could grab the underside of the breather. One photo shows the slide hammer with the modified hook and the last piece of the breather that I hammered out.
It took a number of slide hammers, but I eventually got the rest of the breather out. I only saw a few bits of metal down in the hole into the diff which I sucked up with a straw taped to a shop vac. I will probably change my rear diff oil after it circulates a bit to get any metal bits to the drain plug magnet.
Installation of new breather
I used a 14mm deep socket on an extension to install the new breather with a few taps of the hammer. I did smear some anti-sieze around the edge, but hopefully I will not have to deal with it again.
After install, I bent the flaps of metal back and used some foil tape to seal it up and then covered that with some duct tape. Too bad these breathers are friction fit. If they were threaded in like the rest of the breathers I would have had this wrapped up long ago. If I had not already purchased the breather from the dealer I might have considered buying a Tacoma breather and figuring out the thread side to tap the hole for insertion.
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