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Likely source of oil leak??

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Hey all.....'15 FJ with 45k miles

Noticed some oil seeping the last couple of months. Finally last night on a ride, leak was big enough to drip on my exhaust and billowed smoke around my legs. Before I cleaned it up and started searching, thought I would show a pic and see if there is a common spot that leaks in this area.

The right side is completely dry. Is the shaft seal at the small sprocket a known area? Is dry above the sprocket. I parked on cardboard last night and only spot on ground is where oil is working its way down oil pan and dropping off the drain plug. Nothing at oil filter. Doesn't appear to be the pan gasket but I could be wrong. Thoughts?

fj oil leak2.jpg

Edited by Brian
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  • Brian changed the title to Likely source of oil leak??

As mentioned above, your front sprocket is in need of replacement.  It might be a good time to pull the sprocket and investigate for a leaking seal there.  It is recommended that the front and rear sprockets, as well as the chain, should be replaced as a set.

There is nothing like spending a day riding with friends in the grip of a shared obsession.

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Doesn't have to be an oil leak. I've seen people over oiling their chain make that area look like that.... 

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"It doesn't matter who walks in, you know the joke is still the same"  Ft. Lauderdale, Florida. USA

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11 hours ago, OZVFR said:

Could be the front sprocket seal.

By the way, that front sprocket is in bad need of replacing.

Yup, yup.



50 minutes ago, fddriver2 said:

Doesn't have to be an oil leak. I've seen people over oiling their chain make that area look like that.... 

Also yup.


Also: you're supposed to replace the sprocket nut; it's a consumable. That one has been re-used at least once or twice, and then the last time was not even properly peened into the notch on the countershaft. Read up on the procedure.

Lastly, if you follow Yamaha's insanely taut recommendation for chain slack, you can cause massive strain on the countershaft, and cause a leak or even bend the nose of the countershaft. Use a fairly loose chain slack when you replace the shagged chain and sprockets with higher-quality items.


In this case, odds are it's just a leaky worn-out seal. They get damaged and wear out from road grit sticking to excess lube, and they all wear out at some point.


The parts are pretty cheap, and this is not an overly complex project.


I'd order the seal (33 on the diagram), the nut (36), and probably replace the spring washer (35) as well.

In addition, I'd try to replace that "collar" (18) so that the seal rides on a fresh surface. However, I'm not 100% sure it's replaceable from the outside? Anyone done this?

And of course, it's WAY past time for a new chain and sprockets.


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Thanks for excellent info. 

Chain and Sprockets: I DO have new sprockets and chain laying on a shelf. Reviews for the chain, after I bought it, are not that great so was probably not anxious to put it on. I will order the nut, seal and other stuff. And chain tool.

Will pull out my shop manual.....but is the seal just a standard swap, or is there disassembly involved?

Chain Oiling: From your replies, this might be a likely reason that never occurred to me. Last time I oiled used 90 weight gear oil and would not be surprised if i squirted on too much.

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After my last trip of 6,500 miles and no cleaning mine looked somewhat like that except it did not have the wet look. I run a ScottOiler and chain lube  will build up.  Pulled to sprocket cover off and gave it a through cleaning.  Does not appear to be leaking on my bike just residue from oiler plus road grime.

As for the sprocket don't push it.  Mine is long way from that condition but can see it has wear but has been on there 16,000 miles.  My DID X-ring chain has no stiff links.

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