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Transmission leak after service.

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I capture the oil in a pan, than transfer it back into the empty oil bottles; most bottles have measurement markings on the bottle i.e. 500 mL or 0.5L bottles for the BMW stuff. The quart size bottles will also have a metric scale of 1 L.

I picked up flexible measurement cups for cooking, that I keep in the garage for this type of stuff.
 
johndeeredr said:
Replace my transmission oil on my R1800B . Went for a couple hundred mile ride and noticed some gear oil on my garage floor directly under the transmission. But I traced the steam of oil and it appears to be coming from the top rear or the engine . It’s not coming from the driveshaft seal but above it behind the engine cowling . Is there a vent there? Maybe I overfilled it ? Not sure but would appreciate some advice . I had some Bel-ray 85 - 140 hypoid gear oil left over from my Harley Days. And filled with 1.15 liters. Or 50 .72 oz .
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As with johndeeredr, I found a transmission oil drip on floor.
At 400 miles the trans oil was drained and re-filled with 1.15L of gear oil. Bike now has ~4,200 miles on it.
Why would it take this many miles for leak to appear? Seems to be originating from above the rear of transmission.
 
JRD said:
As with johndeeredr, I found a transmission oil drip on floor.
At 400 miles the trans oil was drained and re-filled with 1.15L of gear oil. Bike now has ~4,200 miles on it.
Why would it take this many miles for leak to appear? Seems to be originating from above the rear of transmission.
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1.5 liter is overfilled ... It most likely is pushing it out of the breather at the back of the transmission.
 
JRD said:
As with johndeeredr, I found a transmission oil drip on floor.
At 400 miles the trans oil was drained and re-filled with 1.15L of gear oil. Bike now has ~4,200 miles on it.
Why would it take this many miles for leak to appear? Seems to be originating from above the rear of transmission.
Click to expand...
Which oil brand did you use? Perhaps you used something off brand, where frothing is occuring within the transmission?
 
- what would cause the vent overflow 4,000 miles after the gear oil change?
- would air pressure be somehow building in the trans and forcing oil out of breather?
- what could be causing the pressure build-up?
- could adding only 1 liter of oil instead of 1.15 liter solve the issue?
 
I had a transmission leak as well. It was coming from the selector shaft seal. Turns out BMW FORGOT to install the circlip that holds the selector shaft in place. That caused major shifting issues, as the shaft couldn't move the shifting forks.

As the circlip sits behind the shaft seal, there's no way to visually tell if it's actually there, except if the shaft itself works it's way out. When my shaft was loose, transmission fluid was able to escape and leak on the deck.

Mike
 
Star-Lord said:
Isn't the gear/transmission oil specification 70W-80...?
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I'm not by any means a chemical engineer, I studied electrical engineering.... I barely passed Chem.1 and 2 in college . With that said, I'm not sure of the differences between the BMW recommend oil specifications of SAE 70W-80 vs the SAE 75W-90

I try and keep it simple, by using what the manufacturer's owners manual recommends; perhaps, there's a significant reason for the leak due to the different oil specification?

Even the 4,000 mile observation could have broken down the oil chemistry which causes it to expand or become frothy...?

Given what I read and the work required to replace the breather vent; it might be easier to get the recommended oil type and due a Transmission and Rear Bevel Gear oil change?
 
Keehn said:
I had a transmission leak as well. It was coming from the selector shaft seal. Turns out BMW FORGOT to install the circlip that holds the selector shaft in place. That caused major shifting issues, as the shaft couldn't move the shifting forks.

As the circlip sits behind the shaft seal, there's no way to visually tell if it's actually there, except if the shaft itself works it's way out. When my shaft was loose, transmission fluid was able to escape and leak on the deck.

Mike
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I have no shifting issues. The trans. oil is originating from the top rear of trans. housing, most likely from the breather.
 
JRD said:
I have no shifting issues. The trans. oil is originating from the top rear of trans. housing, most likely from the breather.
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Good to hear. I bring up my experience because I didn't think BMW would have ever let the omission of a circlip through QA, especially at such a critical spot like the shifting shaft.

Mike
 
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