Differential breather

[DamMechanic]

So after 37k miles my rear differential seal started leaking. Diff oil changed every engine oil change. Heading to WY BDR in four weeks.
I’ve ordered a new seal from two different vendors just to make sure it’s here on time.
But I was wondering why would it start leaking already.
So I tried unscrewing the breather to see if it’s plugged up. DONT DO THAT!
It’s pressed in and you just break the weld off the top cap.
But with that being said, I was surprised that there is no filtration in the breather; it’s just a hole.
Anyone had a similar experience?

 

[DamMechanic]

 

[WJBertrand]

I think there’s a one-way check valve in the breather. Let’s hot, expanded air escape but prevents ingress of anything when cooled. For example a water crossing that suddenly cools the final drive when it’s submerged. You don’t want it to suck water in.


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[DamMechanic]

Nope not even, it just a hole.

 

[DamMechanic]

I would have thought the same thing.

 

[DamMechanic]

Seal area looks perfect!!

 

[TeneKym]

Saw a couple of S10s travelling through and both had diff breathers that went up under the seat.

 

[Madhatter]

all diff breathers are just like that ,very simple .... I guess there are special application breathers but on most applications its just simple.

 

[gv550]

After this little detour…..

I checked my final drive and found the oil was milky, took two changes to get it all out. Definitely nothing preventing water from getting in through the breather.

 

[Jlq1969]

Normally, a seal failure is usually associated with a couple of causes, but very few causes. One of them is usually the axial/radial movement of the bearing… Those marks, if you did not make them during the extraction, are not normal marks of use.

 

[DamMechanic]

Good eye!! That was not me taking the seal out but maybe dragging the wheel off and on over the years. I’ll check it more when I get home this morning.

 

[WJBertrand]

That vent design surprises me. Virtually all cars have a one-way check valve in the vent. The one on my Mustang will actually hold a slight vacuum as evidenced by a “hiss” upon removing it when everything is cold. Wonder if an automotive type vent could be adapted?


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[TenereJourneyMan]

Saw a couple of S10s travelling through and both had diff breathers that went up under the seat.

Hey TeneKym, Like a snorkel? Sounds smart!

 

[Jlq1969]

That vent design surprises me. Virtually all cars have a one-way check valve in the vent. The one on my Mustang will actually hold a slight vacuum as evidenced by a “hiss” upon removing it when everything is cold. Wonder if an automotive type vent could be adapted?


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It would be a good idea. Not for all trips, but if you know that on any of the trips, you may have to cross water over the differential, you could remove the oem breather, and put a 6mm coupling and a rubber hose tied to the rear arm, raise it through the subframe through the front of the subframe so that the other end of the hose is as high as possible. Later, for the rest of the trips… do it with the oem valve… or simply carry the hose coiled on the motorcycle and when necessary, place it
In trucks, in the differential they have a hose that raises the breather valve above the fording capacity

 

[gv550]

So after 37k miles my rear differential seal started leaking. Diff oil changed every engine oil change. Heading to WY BDR in four weeks.
I’ve ordered a new seal from two different vendors just to make sure it’s here on time.
But I was wondering why would it start leaking already.
So I tried unscrewing the breather to see if it’s plugged up. DONT DO THAT!
It’s pressed in and you just break the weld off the top cap.
But with that being said, I was surprised that there is no filtration in the breather; it’s just a hole.
Anyone had a similar experience?

Too late now but at 37k your seal likely was not worn out, just dirty. I would have used a Seal Mate to clean any dirt from the lip to see if would stop leaking. 125k on my original seal, never leaked but I have cleaned it a few times as preventative maintenance.

 

[DamMechanic]

After closer looking, the missing paint is from me dragging the wheel across the face while removing and installing the wheel over the years.
All I can think of is, I replaced the tire 250 miles ago. I lubed up the splines with a bunch of the Yamaha EP grease and durning my last ride on the bike it was 97 degrees out. Maybe that EP grease got under the seal enough to let the oil seal out.

Yesterday I bought the only seal that was within a 150 mile ride to purchase; a good reason to take the Buell Ulysses out for a spin.
Also swung by the hardware store and picked up a black ABS 3” x 3”NPT pipe adapter to machine up a seal driver. Since Yamaha didn’t machine a shoulder in the seal housing to set the depth of the seal, I wanted to make sure it was in square and to the right depth.

 

[DamMechanic]

 

[holligl]

Also swung by the hardware store and picked up a black ABS 3” x 3”NPT pipe adapter to machine up a seal driver. Since Yamaha didn’t machine a shoulder in the seal housing to set the depth of the seal, I wanted to make sure it was in square and to the right depth.

Actually it is easy to use the old seal as a driver and it is also the right thickness to serve as a depth gauge!
I suspect they start leaking due to dirt getting in. I never tried a seal saver on mine. I could really see a difference in the oil changes after replacement.

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