How much oil do YOU put in your front diff?

[4x4mike]

I think Bob's write ups and Toyota say 1.2 quarts. I've filled to the bottom of the fill plug.

A few years ago my front diff drain plug decided to not want to come out. This is pretty common on our diffs so I never tried too hard to get it out. I do remember hitting it with some heat and an impact but for fear of screwing it up I was thankful it was the drain plug and not the fill.

The reason for my question is that I've got a front diff breather that keeps puking gear oil. It's done it in the past especially during and after Pismo where things are getting sloshed around in 4wd and more angle than regular day to day driving. I may have happened here and there but nothing too notable.

In the past two weeks I've done 3 long day trips with 4wd and two at higher elevation. I live around 200' and while one trip was close to home there was some stuckage and fast wheel spinning. The other two trips also had some wheel spinning but were as high as 9000'.

I'm wondering if the bottom of the fill plug is too much gear oil. I can look but I know it's been at least two Pismo trips and many other trips since I last filled the diff and it was done to the bottom of the fill. If it were full it's had it's time to make it out. because the drain plug won't come out I'd be guessing at the 1.2 quarts but thought I'd ask.

I've done some searching and found that those who have the problem extend the breather. I think this is masking an issue and after raising it I'm not sure it would fix it (to the top of the fire wall ads less than a foot).

[troyboy162]

Mine does it often too. Yesterday it let out at least three tablespoons parked in the driveway. It hasn't been filled for over a year and its still equalizing.

[Robinhood4x4]

Toyota may say the capacity is 1.2q, but the fill spec is to fill to the bottom of the fill plug. Make sure, when you fill it, you're on level ground because if you're nose up then you could be over filling it. Do you have a front diff drop...you know, those 1" spacers? I forget which way it tilts the diff on a 3rd gen, but maybe that could be causing an overfill? For what it's worth, I've never had oil spit out of the vent on my 2nd gen or 4th gen.

Edit: Nose up, not nose down.

[4x4mike]

Mine does it often too. Yesterday it let out at least three tablespoons parked in the driveway. It hasn't been filled for over a year and its still equalizing.

Good to hear about the driveway part. I was scratching my head because I swear mine was burping itself over night at home. I spent a little time digging out of the snow a few days ago and remember not seeing or smelling gear oil while in the wheel wells and partially under the 4Runner. Once home and after it sat I had a spot in the driveway and the odor.

I can see how the elevation along expansion and contraction can cause some equalizing but I figured things got figured out thousands of miles ago.

[Seanz0rz]

I don't think I've ever had mine belch out diff fluid. I always fill to the hole, and with the diff drop that might be slightly less than normal, although I have a slight slope in the driveway so it probably equals out.

[4x4mike]

Toyota may say the capacity is 1.2q, but the fill spec is to fill to the bottom of the fill plug. Make sure, when you fill it, you're on level ground because if you're nose down then you could be over filling it. Do you have a front diff drop...you know, those 1" spacers? I forget which way it tilts the diff on a 3rd gen, but maybe that could be causing an overfill? For what it's worth, I've never had oil spit out of the vent on my 2nd gen or 4th gen.

I do have a front diff drop but it's less than a year old. I ordered one years ago and it sat on a shelf as I didn't really need it. After a shock swap a little over a year ago I threw it in. I haven't changed the front diff oil since then but also didn't make any adjustments to compensate for the tilt like you mentioned.

I'm thinking the breather hose might be gummed up a bit and what ever is in there is helping the oil get out? Replacing the hose sounds like it might be a good idea but it also looks like a giant pain in the ass especially since that area is a coated with oil.

[4x4mike]

I don't think I've ever had mine belch out diff fluid. I always fill to the hole, and with the diff drop that might be slightly less than normal, although I have a slight slope in the driveway so it probably equals out.

Sean I read somewhere the hose line is hard for a portion then soft line towards the top. Can you confirm since you've had yours out recently. I've seen it where if exits the diff and at the top but in between is a bit of a mystery. I'm wondering if the change between hoses allows oil to collect half way up. Routing is important so to the proximity to the exhaust manifold.

[Seanz0rz]

I know the top of the diff has a soft line to a formed hard line. I'll grab some pics tonight when I'm home.

The transfer case breather is in the same spit on the inner fender, sure it's not coming from that one?

[4x4mike]

There are several things clipped onto the fender right there. I think two hoses and maybe a wire or two? I know my transmission has a breather. It doesn't not have a hose but is threaded into the top of the transmission and looks identical to the rear diff breather. I'll have to look for the t-case breather.

It had never crossed my mind but the "wet" one goes down towards the diff and not back towards the t-case.

Does the t-case breather have the same breather as the front diff? As in appearance?

[Seanz0rz]

I think so, from memory.