Breather (front diff I think?) very oily...

[ivopivo]

Any ideas why my beeather would be completely covered in sludge?

While installing my transmission fluid temp gauge today I noticed this and was a bit surprised. I believe it’s the front diff breather but not sure. It sits on the driver side of engine bay. There’s nothing that can be leaking on top of it so I’m looking for advice on here as I’m sure someone has come across this.

From some research I’ve done it sounds like I overfilled the front diff (filled until fluid came out) and it just spits some out. I can’t remember if it was like this when I first got the truck but considering I did a pretty thorough engine detail I’m assuming I simply overfilled it.

Thoughts?

 

[thegipper]

Mine has looked like that for years, shouldn't be an issue. It may have been overfilled at one point but I wouldn't lose sleep over it.

 

[2016 4Runner SR5]

Drain the diff and change the fluid. Remove the line, clean it inside and out, and clean out the vent. Clean the whole area and keep an eye on it to be sure it doesn't continue. If it does, find the source of the oil and go from there. This is NOT normal and anyone saying "just ignore it" should be ignored.

 

[BlackCat914]

I wouldn’t sweat it either. I just checked my GF’s and while it’s not that bad, it has some crud on it. It would be very hard to over fill your diff enough to force fluid out the top, especially with the top drain plug out. I also just detailed her engine compartment too.

 

[nobb]

I always slightly overfill my diffs and transmission, it's not a big deal. Mine has looked like that for ages, it's just from minor venting and doesn't affect the level.

 

[ivopivo]

Drain the diff and change the fluid. Remove the line, clean it inside and out, and clean out the vent. Clean the whole area and keep an eye on it to be sure it doesn't continue. If it does, find the source of the oil and go from there. This is NOT normal and anyone saying "just ignore it" should be ignored.

I changed the fluid recently so I’m not sure what that would accomplish. I’ll probably cleanit up and replace the breather and top to see what happens. Is this definitely the front diff breather?

 

[2016 4Runner SR5]

I changed the fluid recently so I’m not sure what that would accomplish. I’ll probably cleanit up and replace the breather and top to see what happens. Is this definitely the front diff breather?

You'd have to follow it down and see where it goes. Due to it's location though I would say yes.

 

[habanero]

Is this definitely the front diff breather?

Yep, it is. A little overfilled appears to be all, especially on the just changed fluid basis.

Clean it up a bit and stick it back in its clip, it has escaped. Should quit puking on its own.

 

[mtbtim]

Like everyone else has mentioned it's fairly normal to see this. But nobody has asked this question, "Were you on level ground when you filled the differential?" If not, you will either end up with an overfilled differential or an under-filled differential depending which direction the front of the diff is pointing, uphill or downhill.

I think it's normal for this breather to escape a little bit of gear oil but not gross amounts. But, better to be a little overfilled than under-filled in my opinion.

 

[mtbtim]

Drain the diff and change the fluid. Remove the line, clean it inside and out, and clean out the vent. Clean the whole area and keep an eye on it to be sure it doesn't continue. If it does, find the source of the oil and go from there. This is NOT normal and anyone saying "just ignore it" should be ignored.

Like the OP said, there isn't any other source of oil on that driver side fender. It's definitely coming from the breather and it IS NORMAL, especially if the differential was a little overfilled.

Suggesting the OP drain the diff he just filled is a waste of gear oil, waste of time and waste of money. The breather goes from a short rubber line, to a metal pipe and back to a rubber line that leads to the driver side fender. The OP could remove the 2 rubber hoses and the metal piping on top of the differential, but I also think this is a waste of time. To get the metal piping free of the differential, you'd also have to remove the vacuum lines. For anyone that has removed a front diff, getting in there to remove the vacuum lines and breather lines is pretty tight and not much fun.

This is not the same style of breather that's on the rear diff that has the spring mechanism that will operate when the pressure in the diff gets high enough to overcome the spring pressure of the breather. The front diff breather is a simple fitting with a cap over the top. There's really nothing that could go wrong with these breathers unless it was completely rusted shut which there's no signs of this on the OPs rig. Hate to say it, but maybe your advice is the advice that should be ignored in this situation.

Now, it wouldn't be a bad idea to clean off some of the built-up oil and crud in the area to have a better idea if it's still puking gear oil out of the breather.

The thing I will add to this post and my other one is the OP should recheck his level and make sure it looks good. The oil level should be right at the bottom of the threads of the fill hole or slightly below, no more that a 5mm.

 

[2016 4Runner SR5]

Like the OP said, there isn't any other source of oil on that driver side fender. It's definitely coming from the breather and it IS NORMAL, especially if the differential was a little overfilled.

Suggesting the OP drain the diff he just filled is a waste of gear oil, waste of time and waste of money. The breather goes from a short rubber line, to a metal pipe and back to a rubber line that leads to the driver side fender. The OP could remove the 2 rubber hoses and the metal piping on top of the differential, but I also think this is a waste of time. To get the metal piping free of the differential, you'd also have to remove the vacuum lines. For anyone that has removed a front diff, getting in there to remove the vacuum lines and breather lines is pretty tight and not much fun.

This is not the same style of breather that's on the rear diff that has the spring mechanism that will operate when the pressure in the diff gets high enough to overcome the spring pressure of the breather. The front diff breather is a simple fitting with a cap over the top. There's really nothing that could go wrong with these breathers unless it was completely rusted shut which there's no signs of this on the OPs rig. Hate to say it, but maybe your advice is the advice that should be ignored in this situation.

Now, it wouldn't be a bad idea to clean off some of the built-up oil and crud in the area to have a better idea if it's still puking gear oil out of the breather.

The thing I will add to this post and my other one is the OP should recheck his level and make sure it looks good. The oil level should be right at the bottom of the threads of the fill hole or slightly below, no more that a 5mm.

Gear oil leaking out of the diff breather on ANY vehicle is not normal, period. Find the source and fix it, period. There really isn't anything more to it.

 

[mtbtim]

Gear oil leaking out of the diff breather on ANY vehicle is not normal, period. Find the source and fix it, period. There really isn't anything more to it.

Actually, it is normal, especially if the front differential was slightly overfilled. I use to think like you do but I've worked on numerous 3rd Gens over the last couple years and it's common to see some gear oil residue around this front diff breather. I have a 98 and 2000 3rd Gen and there's signs that small amounts of gear oil have come out of the breather over the life of the vehicles. If it pukes out a gross amount of gear oil, that means the person really overfilled it.

There is no source to find or fix. Everyone who's contributed to this thread other than you already knows what's going with the OP's rig. I'm not trying to be a jerk here. Your assessment and suggestions for the OP are not correct.

 

[ivopivo]

Definitely on level ground and checked 5 times. I overfilled it a bit (it's to the threads, but should be 1-2mm below from what I remember) so sounds like it's normal. Plan is to clean up the tube and replace breather (replacing breather just because I like to replace random things not for this reason) and see if it happens again. I doubt it will. Thanks guys.

 

[catrains]

Definitely on level ground and checked 5 times. I overfilled it a bit (it's to the threads, but should be 1-2mm below from what I remember) so sounds like it's normal. Plan is to clean up the tube and replace breather (replacing breather just because I like to replace random things not for this reason) and see if it happens again. I doubt it will. Thanks guys.

when my truck was new and winter hit using 4WD I noticed some oil at the front diff vent ... did not see it before like for 9 months . brought to dealership tech looked at it said that will happen when the 4 WD is engaged as the gears do heat up the oil ... condition normal..

so now 18 years later I last month noticed the front diff vent had some oil on it .. last time I changed/added oil was 3 yrs ago ... It will occur and is not a problem .. check the oil and level and if its good no problem..

if the front end is higher than rear I would expect some to vent out but NO damage..

this is a good way to reduce any frame rust in that area..

IMO clean up the vent and hose..

 

[Kanoe]

One point not mentioned yet is that this issue has been addressed in several (many??) threads over the years. Many of us have had this happen, myself included.

Story seems to be the same every time. Person does a drain and fill on the front diff and all is good... until the first time you drive for an extended period in 4wd. then it pukes.

Mine did it one time and never again.