Final Drive Breather

[B4ndit]

Seems my final drive breather is letting moisture in. 1000 miles from last oil change and its all milky again. Soent about two hours in heavy rain in that time.

Does the breather just pull off so it can be checked for integrity or cleaned. Or is there some sort of fancy way of taking it off.

Quite happy to buy a new one if the old one has had it. 2011 bike btw with 10500 miles. Four finla drive oil changes this year alone for one reason or another.

 

[Pukmeister]

I wonder if condensation is forming inside your FD when it cools down after riding? I'd expect the breather to be designed to let excess pressure out but not let any water in.

Just done a service today (2008 bike without FD breather) and got milky oil out (was clean 6 mths ago) but I guess that's due to me recently riding through floodwater.

 

[Kenny Rodkiss]

It just pulls out, the top half is just folded over on itself.

 

[B4ndit]

It just pulls out, the top half is just folded over on itself.

Cheers mate. Job for tomorrow night.

 

[B4ndit]

I can't understand how water is getting in. Oil changed one week and 1000 miles ago. Bikes been washed without a pressure hose since then and ridden through a couple of hours of rain, some heavy, thats it.

On the previous change which I only kept in for 160 miles the oil came out like new.

It would be interesting to see how much water you need to make it go a yellow milky colour.

 

[Deleted account 190920001]

I don't have a breather on mine but it seems to be a common complaint and it gets worse if you go fording. Hot FD plunged into cold water (possibly cold rain/wet Road in your case) and as the air contracts it sucks in water. There was a project over on Adventure rider to convert the breather to connect to bellows effectively sealing the system but still allowing expansion so the seals don't blow out.

 

[B4ndit]

I don't have a breather on mine but it seems to be a common complaint and it gets worse if you go fording. Hot FD plunged into cold water (possibly cold rain/wet Road in your case) and as the air contracts it sucks in water. There was a project over on Adventure rider to convert the breather to connect to bellows effectively sealing the system but still allowing expansion so the seals don't blow out.

Pretty poor design by the looks of it. One of this parish chnages his FD oil every 1000 miles. Maybe that needs to be the service requirement for this oil. Good job its only 180 ml of the stuff.

 

[(RIP) Arkwright]

Good job its only 180 ml of the stuff.

That's not enough oil, I know it's what BMW recommend but that's only to stop them having to change the outer seal, 180ml has the potential to starve the pinion bearing, (ask Mikeyboy!)

Personally I put 240ml of 85/140 GL5 in every oil change, (which I do every service), still on the original outer seal, (so far) but who's to know!

 

[birdseye]

I would not have expected the oil to get milky in that short period of time and just from expansion and contraction in normal use. Have you checked the swing arm? I had the bellows between swing arm and engine come unseated and the swing arm start to fill with water. I am wondering if there is water in yours and its getting past the seals into the bevel box

 

[Deleted account 211025001]

.................I had the bellows between swing arm and engine come unseated and the swing arm start to fill with water. I am wondering if there is water in yours and its getting past the seals into the bevel box

There is often a small pool of water sitting in the open part of the FD as it easily gets in there from the aperture at the bottom of the s/arm. Surely though, the oil seal will stop water entering just as it stops oil escaping - it's what a seal does?

I can't comment on whether the issue is the breather or not but I've never had any milky oil on any of the services on my (no breather) '05 GS.

Andres

 

[birdseye]

The design of a lip seal is such that it seals much better in one direction than the other. Plus water in the swing arm could be ( without going into the garage to look) higher than the oil level in the box.

At this time of year, expansion and contraction as the box warms up in use and cools down afterwards will suck fresh mosture laden air in. But I wouldnt think for a moment that there would be enough moisture in there to cause milkyness. So there has to be another way that water is getting in.

 

[Deleted account 211025001]

.................... So there has to be another way that water is getting in.

Well, stating the obvious, the only places are the input seal, the two seals either side, the breather or the ABS sensor.

Maybe the small o-ring on the ABS sensor is missing or knackered? I't very easy to miss when removing/refitting the sensor.

Andres

 

[G5RJO]

Water fills up the swinging arm if the front (Gearbox to swinging arm) bellows split or become dislodged.

On its way down it will shag up the swinging arm bearings and the bottom UJ on the driveshaft then pass the pinnion oil seal flooding the final drive with milky watery oil.

Been there, done the repair. Mucky messy job.

Roger.

 

[Ali-bear]

Brilliant design there fellas.