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YZ250 Nightmare!

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Hi, 

 

Firstly ill introduce myself! I ride a 1999 YZ250 mainly on motocross tracks. I haven't posted here before but im regularly on here looking through posts and gathering lots of knowledge from you guys! 

 

My question is this...

 

I recently changed my water pump seals because i was leaking water from the weep hole (I left the bearing and shaft as they looked fine) and basically when i last went riding it my gearbox got stuck in gear (she was a tad hot) so I thought I'd better check to make sure I put oil in the tranny, Of course there was oil there (I knew there was i was just being paranoid) but it was a grey colour.

 

Any ideas why my bike was stuck in gear? (It was fine to ride again once it cooled down)

 

Now, before I stopped the leak, the oil wasnt going this colour, it was fine, which makes me think I have a problem elsewhere. 

 

Today I drained my oil, filled it with fresh oil, ran the bike for literally 2 minutes and drained it again, and it is this grey colour again! I can't determine if there is less water in my rad but I don't reckon that water could be getting into the oil! I heard a greyish oil can be caused by aluminium contamination, and i think the stock clutch plates are ally, but why would it start making the oil grey now when it was fine with the last lot of oil which was about 1 hours riding ago? (I didn't abuse the clutch in this time either) 

 

The only thing i think i could have done is fitted my new seals wrong in my water pump, but surely if I had done this then it would still be coming from the weep hole as well? 

 

Do you guys have any ideas what my problem could be? I've got a bottle of the grey oil my phone so if anyone wants to see it i can email it over (might be able to tell me straight up whether its water contamination or not!)

 

Thanks for all your help!

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Check your water pump seals again.  If you put them in backwards, they will not stop coolant from leaking past.  Since you are seeing milky oil (classic sign of water contamination), your seals are a prime suspect.

 

If you put the inner seal in backwards, and the outer seal in correctly, then the coolant would be leaking into the case, but you probably would not see anything coming from the weep hole.

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Thanks for the reply! I'll pull it apart tomorrow and have a look at the seals again, put it back together and let you know how if it's fixed the problem.

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