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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: dfx on December 21, 2014, 02:35:28 PM

Title: Oil leak underneath bike
Post by: dfx on December 21, 2014, 02:35:28 PM

Hi,

1984 K100 120k km. I'm sure someone must've seen this, what is the likely reason for the oil? What is the unit covered in oil? The gearbox?
Thanks!

Title: Re: Oil leak underneath bike
Post by: Scott_ on December 21, 2014, 02:43:02 PM

Most likely the clutch nut o-ring. Very common as a source of oil leakage as our bikes age.
The oil covered component is the "intermediate gear housing", and it also contains the clutch assy.

Title: Re: Oil leak underneath bike
Post by: i-man on December 22, 2014, 12:56:20 PM

would it be possible for you to post an exploded view of the part you're talking about? I have the same problem. i looked it up and didn't find a match for clutch nut o ring.

thanks

Title: Re: Oil leak underneath bike
Post by: F14CRAZY on December 22, 2014, 04:50:32 PM

(https://www.rbracing-rsr.com/turbo/clutch/bmwk100_clutch.jpg)

#17. Definitely want to go to the dealer for it as I tried using one from an auto parts store by eye-balling the old one and it leaked

Title: Re: Oil leak underneath bike
Post by: dfx on December 22, 2014, 05:03:50 PM

So it's the o ring at number 17? Is it engine oil or transmission oil that is leaking?

Title: Re: Oil leak underneath bike
Post by: Scott_ on December 22, 2014, 07:05:29 PM

Yes, #17 is the o-ring that leaks. The oil leaking from a bad o-ring will be engine oil.
If you wipe your finger along the bottom and give it the sniff test, you should be able to definitely tell if it has the strong 'sulfur' odor of 90wt gear oil or not.

It is possible for gear oil to leak from the bell housing area, but less likely than engine oil.

Title: Re: Oil leak underneath bike
Post by: Scott_ on December 22, 2014, 07:16:18 PM

(http://www.maxbmwmotorcycles.com/fiche/Diagrams/B0000545.png)

IF, the oil has the gear oil sulfur odor to it, the most likely cause would be the clutch push-rod shaft seal. (#12 in this diagram seals the push-rod #13 in previous diagram)

Title: Re: Oil leak underneath bike
Post by: Motorhobo on December 22, 2014, 09:30:06 PM

Quote from: i-man on December 22, 2014, 12:56:20 PM

would it be possible for you to post an exploded view of the part you're talking about? I have the same problem. i looked it up and didn't find a match for clutch nut o ring.

thanks

Exploded parts diagrams are on several dealer sites. I use bobsbmw.com because it's easy to navigate. Look here...

http://store.bobsbmw.com/microfiche/BrowseSeries.aspx (http://store.bobsbmw.com/microfiche/BrowseSeries.aspx)

Title: Re: Oil leak underneath bike
Post by: TimTyler on December 23, 2014, 12:01:01 AM

If you choose to replace the O-ring there are other maintenance tasks worth performing at the same time.

Clutch -> Spline lube
Engine -> Rear Main Seal replacement
Clutch -> Friction disk (measure and replace if necessary)
Gearbox -> Tighten Grub Screw if lose http://www.motobrick.com/index.php?topic=4302.0 (http://www.motobrick.com/index.php?topic=4302.0)