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dhilt

Oil leak from bottom of crankcase bolt.

19 posts in this topic

Anyone have issues with the allen bolts leaking that (looks like) hold the crank case together.  They are behind the frame and I don't see anyway to get to them.  Do they have replaceable washers?  Not sure why its leaking.

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It's probably not leaking. It's probalby leaking from somewhere else and dripping down.

Pressure wash the motor and watch.

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It's probably not leaking. It's probalby leaking from somewhere else and dripping down.

Pressure wash the motor and watch.

I cleaned it up, put a light under the bike and lied right on the floor and watched it leak from the bolt head.

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That's what I'm afraid of. Do you know if those bolts have washers on them or do you think the case might be cracked? I can't see any cracks from the bottom or side but maybe something is cracked where the threads are.

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That's what I'm afraid of. Do you know if those bolts have washers on them or do you think the case might be cracked? I can't see any cracks from the bottom or side but maybe something is cracked where the threads are.

 

 

You should download a service manual  from Yamaha 's website

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So I just checked the service manual.  I don't see any washers on those bolts.  I wonder why they are leaking, they are tight.  Hmmmmmm

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They are probably leaking because you have an inner gasket that has failed, or, a crack in the case.

Do not over tighten any bolt.

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None of that sounds very good.  I don't see any cracks from the outside anyway.  Sounds like a MAJOR overhaul to open up that case and put in new gaskets.

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None of that sounds very good.  I don't see any cracks from the outside anyway.  Sounds like a MAJOR overhaul to open up that case and put in new gaskets.

 

It is what it is. 

It won't fix it self.

You can ride it until it goes catastrophic, by just adding oil often.......but I wouldn't.

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None of that sounds very good.  I don't see any cracks from the outside anyway.  Sounds like a MAJOR overhaul to open up that case and put in new gaskets.

 

There are no gaskets between the two case halves...   they are machined and matched at the factory and assembled with no gasket

 

I believe they use some Yamabond but that is it

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There are no gaskets between the two case halves...   they are machined and matched at the factory and assembled with no gasket

 

I believe they use some Yamabond but that is it

You are right, no gasket. 

I was thinking Honda.  

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If you have to pull the motor to get to the bolt, so be it.  If you do not see any external cracks and it's just coming out where the bolt it, it's somehow getting past the threads.  I'd just drain the oil, angle the motor so any additional oil pools away from the bolt, clean up the threads with contact cleaner and q-tips, wait for it to dry, put some locktite at the beginning of the threads (maybe drip some down the hole), then put some high heat silicone on the rest of the threads and up to the head.  Then make sure it's torque'd to the proper spec.  Also, just replace the bolt to be extra safe.  Anything else, You'd have to split the case and I think that would be a bit premature at this point.

Edited by mch

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If you have to pull the motor to get to the bolt, so be it.  If you do not see any external cracks and it's just coming out where the bolt it, it's somehow getting past the threads.  I'd just drain the oil, angle the motor so any additional oil pools away from the bolt, clean up the threads with contact cleaner and q-tips, wait for it to dry, put some locktite at the beginning of the threads (maybe drip some down the hole), then put some high heat silicone on the rest of the threads and up to the head.  Then make sure it's torque'd to the proper spec.  Also, just replace the bolt to be extra safe.  Anything else, You'd have to split the case and I think that would be a bit premature at this point.

Thank you for your suggestions.  That sounds doable for me.  I called the dealer and he said he hasn't heard of that happening.  He said he would need to look at it.  Not sure I would waste my time taking to him, just to tell me what you just said.  :-)   

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I wouldn't split the cases over that kind of leak. There are no sealing washers, and no gaskets. The case is sealed with a sealer out of a tube "Yamabond". Just snug up the bolts and check oil levels to get a idea of consumption/ leakage. Clear clean oil sometimes migrates from another unseen area.

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A oil leak as you describe nearly never happens unless there was a little Yamabond squeeze out that someone picked at and was able to pull the sealant out of the cases.

 

Reclean the engine. Run it and then blow a little talc at the area. It will only stick to the oil, oil runs down hill. The highest point with talc on it is the leak.

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imagejpg1_zps36bd0d3b.jpgimagejpg1_zpse9bb9a40.jpg

Was thinking about your issue while finishing a job this evening. A few IFs, If this is the area you have leakage, it's possible that the bolt with the paint pencil is leaking. That bolt is a thro back from the steel frame models where they had 3 drain bolts and this one drained a small pocket of oil on this side of the sump. Short story, this bolt has a copper washer and is a drain bolt. It could leak down not the lower case half bolt. Look and see if this bolt is sealed with a copper washer.

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Thanks Maddog.  Not the bolt though.  I have a pic, but don't know how to upload it.  Its the most forward bolt (towards the front wheel ) on the bottom of the motor.  Best seen by removing the skid plate.  It doesn't have a washer that I can see. Its an allen head bolt.  

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