Oil in water? (250R)

[HondaHarry]

OK, I was just taking pics of my silencer for Dammit! and decided to look in my overflow tank, and saw a little bit of dark oil floating on top of the antifreeze. I think the mechanical waterpump seal is shot? I dont think its the head gasket, I checked to see if I was getting bubbles in the cooling system and didnt see any, and the oil leads me to think its coming from the gearbox, (I always looked at the level thru the tank and never pulled the cap, so I dont know how long its been doing this, I changed the gear oil 2 rides ago, and I didnt notice any water in it then. (the motor had just been rebuilt last winter, but I dont know what all has been done, I know that both sidecovers were removed during that rebuild, but dont know if the waterpump seal was replaced then or not. Anyways the coolant was fresh then and still looks like it was just put in yesterday, (it really hasnt been ridden much, id say it has 20 hours on the rebuild if that) anyways, my questions would be, What else should I look for to find the cause of the oil in the water? Should I change it and keep an eye on it? Or do I just get a seal and replace it? If so, any advice on what it takes to change that seal? Thanks.

[Wickedfinger]

Drain the crankcase oil and look for anti-freeze and sludge in there. It dosent sound to me like its a head gasket - you didn't mention white smoke - so its probably just the water pump.

[TimSr]

Usually when the waterpump leaks, you get lots of coolant in the gearbox, but rarely do you get any oil in the cooling system, and when you do, its not much. If you oil is not milky gray, your water pump is probably fine. Id chech oil, change if necessary, and flush out the cooling system, and then keep an eye on it. Its possible it may have had traces of oil in from several repairs ago.