(YZ250) Help me find this oil leak.

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9/19/2017 11:34 AM

So I posted here a couple of weeks ago about a gas leak on my 02' YZ250. After a new float bowl gasket and a float height adjustment, that has problem has been fixed. Now I've got another one that's got me stumped. Now that I don't have gas running down the left side of the engine, I noticed that I have oil around the left side cases around the area where the clutch actuator shaft is housed, and the countershaft.

When I first saw it, my initial thought was that the countershaft seal was leaking. After pulling the sprocket, I'm confident that's not where it's coming from. I pulled the flywheel cover to make sure I wasn't getting oil from the crank seal, and it's dry in there.

I have examined the hell out of the cases for cracks and I don't see any, however, there is a spot on the cases where the previous owner had it welded. It's on the end of the molded part of the case where the clutch actuator arm is housed. That being said, the weld looks solid, and based on the oil trail, I don't think it's coming from there anyway.

Here's the two suspects: 1) The crush washer for the bolt that holds the actuator arm in place is mangled to hell. There was oil behind it when I pulled it out, so who knows. 2) In the image below (not the best pic I could find) the chain has derailed at some point and gnawed into the part of the case where the arrow is pointing. The gash was about 2-2.5mm deep, but I didn't think it was deep enough to get through the case.

Here's the final clue: It only leaks when the bike is running. While sitting on the stand, I get nothing, it's only after I've been riding. Help!!!

Photo

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9/19/2017 12:04 PM
Edited Date/Time: 9/19/2017 12:14 PM

What type of chain lube do you use

If you dont think its the cs seal, I would look at the shift shaft seal and whatever the seal next to it is. You could just replace all of them anyway since theyre cheap and easy to do

You could also try jb welding the gash to be sure its not that.

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9/19/2017 12:52 PM

rmoto003 wrote:

What type of chain lube do you use

If you dont think its the cs seal, I would look at the shift shaft seal and whatever the seal next to it is. You could just replace all of them anyway since theyre cheap and easy to do

You could also try jb welding the gash to be sure its not that.

It's an x-ring chain so no lube. I thought shift shaft seal also, but it's lower than the "oil line" that I'm seeing on the case. I'm probably going to go ahead and replace the CS seal even though I'm still not convinced that's where it's coming from. I actually have some JB Weld in my possession as we speak. I'm going to dab some in that gash to rule it out as a suspect.

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9/19/2017 1:57 PM

Ruled out the powervalve breather hose?

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If you're not mixing gas, you're not haulin ass.

9/19/2017 3:43 PM

TrailDigger wrote:

Ruled out the powervalve breather hose?

Yea. I like they way you're thinking, though. Thanks.

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9/19/2017 3:55 PM

I would throw some epoxy in the gash for good measure, and change the crush washer. They're cheap and you mind as well for peace of mind.

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If you're not mixing gas, you're not haulin ass.

9/19/2017 4:11 PM

TrailDigger wrote:

I would throw some epoxy in the gash for good measure, and change the crush washer. They're cheap and you mind as well for peace of mind.

Just placed an order for the crush washer and a new counter shaft seal. Did the jb weld thing earlier today.

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8/30/2020 2:04 PM

i got a leak on the case is it normal the bike got 20 hours got it from the dealer ? Photo

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8/30/2020 3:35 PM

Crush washer possibly and you also have an oring on the cs as well. You may be anle to get to it with the seal out

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