Author Topic: 85 k100 Oil Leak behind alternator ?  (Read 548 times)

Offline Atabeach

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85 k100 Oil Leak behind alternator ?
« on: April 18, 2026, 04:17:17 PM »
Not good. Oil leaking from behind alternator…What are my options ? All cleaned up now but oil seems to appear every couple of days. TIA
Ok UPDATE! Main seal leak…Photo #3. Are these 2 leaks related?
  • Ponte Vedra Fl
  • 1994 k75 Standard, 1985 k100 ; FYK! 2002 Harley Dyna, & my favorite 2006 Vespa LX150!

Offline Laitch

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Re: 85 k100 Oil Leak behind alternator
« Reply #1 on: April 18, 2026, 07:52:50 PM »
What are my options ?
The first option is to use a pencil, or slender Phillips screwdriver, as a pointer instead of using your finger; either has less diameter, greater reach and would enhance specificity.:laughing4-giggles:

Your alternator's shaft seal might be leaking. That shaft connects with the countershaft that is turned by the crankshaft while the engine is running or while the starter is turning. As the seal wears, the amount will probably increase but not gush, thus eventually requiring Simple—or perhaps Soylent—Green and copious rags for cleanup in time for visitors. If this relic hasn't been ridden much, more riding could possibly stop the leak.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline Atabeach

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Re: 85 k100 Oil Leak behind alternator ?
« Reply #2 on: April 18, 2026, 08:01:48 PM »
Thanks Laitch! The leak appears to be getting worse. It has become my daily driver. Further, someone on MOTOBRICK commented this could be from a main seal leak…I have a leak out of the weephole at the bottom of transmission …can these be related? 😳 I will use a pencil in the future.
  • Ponte Vedra Fl
  • 1994 k75 Standard, 1985 k100 ; FYK! 2002 Harley Dyna, & my favorite 2006 Vespa LX150!

Offline Laitch

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Re: 85 k100 Oil Leak behind alternator ?
« Reply #3 on: April 18, 2026, 08:13:59 PM »
The weep hole drips oil leaking from the engine output shaft O-ring, the rear main seal or from a transmission cover seal—the usual suspects. Transmission fluid smells like sulfur.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

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