Blocked Front Diff Breather = Blown Axle Seal?

Noticed my truck was leaking a bit of gear oil from the passenger's side of the front diff (where the CV meets the differential). Replaced the seal yesterday (what a bear!) and so far no leak.

However, I started looking into it more and I keep seeing indications that if my front diff breather is plugged, it would build pressure and fluid would escape at the weakest point--that seal. Is that a possibility?

I recently got a LOT of mud all over that area a month or so ago, so it's a possibility that I did plug the breather. Going to look today. I'm assuming I'll find it somewhere on the top of the diff--maybe with a hose going under the hood?

 

More than likely just the seal. The breather is run up high under the hood.

 

That can be completely true with solid axles that have open bearings - where the oil that's inside the diff actually is inside the axle tube and lubricates the wheel bearings.

The assumption would be ...YES.... a blocked breather tube can't be good. I used to own a 96 tacoma that (from what I remember), had ONE breather that was for both the front diff & transmission. These never trucks could have one breather for each....so you'd want to find each breather and check them.

I had issues on my 96 where the oil would leak out of the breather tube (not overfilled) - so I extended the breather tube up to the master cylinder. This way....I wouldn't lose any oil and it would stay clean and water/mud free.

 

This.

Highly unlikely there is a block in the vent, most people don't start looking at that until they have lost more than 1 seal. If you lose another, you'll have to start looking at odd ball things. I believe the breather for the front diff is next to the primary brake system components.

 

Thanks! I'll double check it today since it sounds like it is easy to get to. Just thought it was weird that it randomly went.

Truth be told, I am not confident that this one is any better with how much I struggled with the new one, but time will tell.

 

yup front diff breathers (plural) are just below the master cylinder on the inside of the inner fender. There is the main one (bigger tube) that is for the main diff case, and the other (smaller) that is the breather for the front diff actuator.

Trans breather sits on top of the bell housing.

Tcase actuator vent runs to the case of the tcase, then the tcase has a breather that lays on top of the transmission.

 

Looked this morning. It's still leaking. I'm not taking the thing apart again just to fight with another seal for 3 hours and never get it seated quite right. I'll have someone else do it at that point.

Noticed the two breathers have metal caps on them. The smaller one's cap flops around on the hose, the larger one's is pretty firmly seated onto the hose. Is that how they should be?

 

The only way you'll know for sure that its not blocked (or something is wrong with the cap) is take the cap OFF the hose and blow into the end that was on the hose. You should be able to blow thru it easily without much (or any) resistance.

 

I see how it works now. Took it off, air passes reasonably easily.

 

I had the dealer do this. Wasn't going to try to fight with it again myself. Couldn't get the stupid thing to seat correctly without destroying it. Well worth the price to just have it done right.

The service manager told me he's had bad luck with aftermarket seals leaking again within a few days when they've used them, but they've never had an OEM one come back. So far, so good. Also said my truck is in fantastic shape for 110k and needs nothing...good to hear from a guy whose job it is to find issues in order to sell more service.