Sorry to be so slow but I admit I've been dragging my feet on this.

I finally reassembled everything, aired up the tires to 38PSI-Fr/41PSI-Rr, and went for a 24 mile test ride. First, the “can of marbles” sound from the Transmission is gone. I’m not sure if replacing the 6 Bearings or the new Clutch components eliminated the noise but for sure it’s not there anymore. All went well during the ride. The Transmission shifts gears smoothly and the Clutch engagement/disengagement is fine. Before the test ride I replaced the Rear Differential Oil with Silkolene BOA 80W-90 High performance Hypoid gear oil. After the test ride I replaced the Transmission Oil with Silkolene BOA 80W-90 High performance Hypoid gear oil.

Before draining the old Transmission Oil I noticed Transmission Oil on the right half of the Centerstand…wet and fresh, not old and greasy. Further investigation noted it had leaked past the Transmission Output Shaft Seal (all new seals in the trans) and got past the Rubber Boot between the Transmission and the Swing-Arm. When I drained the Transmission Oil I only removed the Drain Plug. I didn’t open the Fill Port. This is noteworthy because the Transmission Oil gushed from the Drain Port. Now I’m suspecting the Transmission Vent is plugged up because in order for the oil to gush forth there had to be greater than atmospheric pressure inside the Transmission. I had specifically replaced the black rubber external Breather (BMW P/N: 23-00-7-693-739) since the original one was dry and hard. I also observed the black plastic internal Breather (BMW P/N: 23-00-2-333-147) was still good and could pass light.

So now I’m suspecting the Transmission Housing passage between the two Breather parts is plugged. I never checked it and just assumed it was fine…big mistake! If this is true then it solves the mystery of the Bubbles in the Transmission fluid last September (see previous posts in this thread). As the oil inside the Transmission heats up it simultaneously heats up the Air trapped inside. As the Air heats up it’s pressure goes up. Some of the pressurized air becomes entrained in the Transmission Oil. Opening either the drain or fill ports reduces the air pressure on the oil and the entrained Air can then escape from the Transmission Oil.

I’m going to confirm if the Vent is plugged by connecting compressed air to the Fill Port and listen if I can hear it escaping or not escaping from the Vent. It may escape from the Transmission Output Shaft Seal so I’ll listen there as well. This should reveal if the Vent is plugged or not. Since I don't have an air compresssor I put the word out to my riding buddys to borrow one of theirs...I'll have an update hopefully soon.

I am now also wondering if anyone else who has experienced Transmission Seal leaks has a plugged vent?

you have a vacuum pump that you use for bleeding brakes. use it

Capital Idea Bill! Thanks!

If it turns out that it is plugged this makes me think what would stop this from happening again post repair? A design weakness? I'm not riding on dirt roads all the time. A casting flaw?

I'm now considering to put a hose fitting on the Fill Port instead of the Plug. Route the hose mostly straight up and cap it off with a small filter. At least I'd know this vent is working because I could easily test it every time I replace the Trans Oil.

Maybe some "low suds" tranny lube.;)

just rolled through 10K miles and I got it too
 

I have that marble sound, though can of marbles to me implies a tinnier sound than what I hear. The sound in mine is more dampened and a lower tone, but definitely sounds like marbles bouncing around in a heavy cast part (I should clarify an aluminum cast part as opposed to a steel part - the point being there is no "ring" to the sound, i.e. poor material to make a bell from). Similar scenario, it makes scary noises on the center stand in gear at idle, etc. I have no idea... it never does it under load while riding, only when I come to a stop. Strange indeed. A small problem in the process of becoming big? Don't know. The thing that makes me think it is clutch related is a similar tone noise is made by the clutch sometimes when I hear it engage with a clunk. BTW, the clutch lever seems to have to be let out over half way before it starts to engage... just feels like a worn down (not out) clutch to me, but that is based on cage experience, not two-wheeler experience.

I have just been playing the ostrich on this one and may live to regret it. Ever notice how the word "ostrich" has a distinctly German looking construction to it?

LOL...and here I thought High Detergent Lubricants were the best! :confused:

Good point ranadrew...and some say the Germans are a humorless people - I beg to differ:
YouTube - ‪berlitz junior‬‏

Here is the new more reliable Transmission Vent. Now I'll never have to worry if the Transmission Vent might be clogging itself all over again thus causing the Transmission Fluid to entrain air and diminshing it's lubricating properties.

I initially had some concerns about interference with my right foot but so far it's not a problem. Riding up a steep hill (>45 Deg) might cause some trans fluid to flow up to the Filter but I'll risk it for now. If it becomes a problem I can re-route it up under the Tank.

Parts List:
1. Aeroquip - AN Flare to Metric Adapter; 06AN Dash Size; 18mm x 1.5 Pipe size; Aluminum; Blue Anodized.

2. Aeroquip - Socketless Fitting; 06AN Hose Size; 90 deg Elbow; Aluminum; Red.

3. K&N 62-2470 Crankcase Vent Filter.

4. Thermoid P1132 Crankcase Ventilation Hose.

5. Plastic Ty-Straps.

6. Short Plastic Tube between item 3 and item 4.

7. BMW Transmission Fill Plug Crush Washer.

Pics...
http://forums.pelicanparts.com/uploa...1310518961.jpg

http://forums.pelicanparts.com/uploa...1310518988.jpg

http://forums.pelicanparts.com/uploa...1310519021.jpg

So did you verify that the vent was clogged? Or is this fixing something that wasn't broke?

I'll be honest with you R111S, I think this is over-kill.

I'm convinced the vent is clogged but no I did not tear off the whole back side of the motorcycle to verify my suspicion. :eek:

If you read my saga of woe in the preceding posts you'll see it all makes sense.

Tell me, why would the Trans Fluid gush from the Drain Port while the Fill Plug was still in place? There had to be pressure behind it. Only a clogged vent would allow this pressure to build up in a hot transmission.

You have got to be kidding. Right?

I can see why you'd say that but what price for peace of mind while traveling far from home?

Besides, it'll be a good conversation starter at Rallies.

"Hey whats that?". "Oh, that little hose?" "Yes". "That's an oil feed line to the Supercharger Bearings". "Supercharger!???"...

No. Please read all of my previous posts if you haven't already. Surely you know about air entrainment in oil. This is why the Transmission is vented.

1. Why did it clog?

2. If I un-clog it will it not clog again?

3. Will this new vent clog?

Please Guys, you're making me feel like I should have never posted this.

Posting it is not the issue Dan. There is no design flaw with the factory vent. Foaming grease has to do with the quality of the product, and if the grease is extremely cold.

Does anyone have a tranny that's torn down so we can view the vent. I'd take a piece of tie wire and roto root that bugger out. I think it has bearing chips clogging it up.

Dan, I'm glad you posted this. It gives rise to a good discussion.

You might have installed a bad breather, which does not pass air. We were told in Service School about this happening.

My comment is to a lesser extent about the solution (rather than establishing that there is a problem and fixing it) and to a greater extent that you just couldn't be serious about riding around with that thing hanging off your bike. But I guess you are.

You've already been outdone, though, before you even knew it. Anyone here remember the chrome intakes with the filter on the end, that were sold for the K75/100? I think Luftmeister sold them, but I could probably be sued for slander if that turned out to be incorrect. They were that ugly. It was like when kids put a huge chrome Moroso filter on top of an otherwise stock motor, except this thing stuck straight out the right side of the K motor like a Harley chopper filter. I was just flabbergasted when I saw one, ridden by a BMW mechanic of all people. I couldn't believe it was a product that was actually sold in a catalog, rather than being something the guy fabbed up out of some vacuum cleaner parts. Your transmission vent looks factory-original in comparison.

I agree it's not the most elegant solution...but saves me lots of time in comparison to fixing the OEM Vent. Take off body work, remove rear sub-frame, remove airbox, then reach the External Vent (4). Then I'd have to apply a vacuum to suck out what ever is clogging it. In the process I'd risk damaging one of the several Shaft Seals because of the vacuum...nope I'll just be content with this solution.

Actually I looked at the original External Vent (4) as well as the Internal Vent (9)...both were fine but I replaced No. 4 because it was dry rotted. What I failed to do was verify the casting passage between the Internal and External Vents was free to pass air.

The External Vent (4), made of black rubber, is simply pushed into the casting and is held in place by a small lip profile that engages the trans casting profile. If it was plugged and thus holding air pressure in the Trans I'd think it would pop out. Believe me it wouldn't take much.

Here's a line-art of the OEM Vent (actually two parts and a cast passage between):

http://forums.pelicanparts.com/uploa...1310523672.jpg

You could blow in the hose that you have added, with your lungs, to determine if the factory vent is clogged, with no danger of damaging seals.

On the plus side your fitting and hose will make for easier filling when changing the fluid.

On the negative side, I see your vent as a way for moisture to get into the transmission when riding in the rain or washing the bike.