I have a yz450 2008. I am the second owner. I have ridden the bike for 18 hrs. (i think the bike literally has 20hrs on it now. Up to about 4 hrs ago everything was fine regarding the color of the coolant. No coolant has been seeping from the weep hole. Now when i check the coolant before i ride, i notice the color is fine, but the clarity is not quite like my other bike and I notice floating on top or in the water a couple of small silver flakes. I also noticed tonight a tiny piece of rubber floating, actually two of them. Before i noticed the rubber i had little black polliwog looking things in the water. There was only one or two and when i would fish them out and rub them between my forefinger and thumb they would dissipate. I flushed the coolant system with distilled water two different times but the flakes are evident now (I do not remember them before). I inspected the impeller and it seems fine, no noticeable wear on the case behind the impeller. I can move the impeller up and down slightly but it does not seem to contact the case. When i removed the water pump cover i noticed corrosion around the spout which i cleaned and shined up. The bike does not use coolant, seems to run fine. I don't notice oil in the water, but i do notice the clarity is just not like my other bike. Is it possible that the bearing has just a little too much free play and it is wearing the rubber washer? Is it possible that one of the seals is starting to wear and is in the infancy stage of failure? Is it possible that one of the seals is wearing on the shaft creating the flakes? Any insight would be helpful. Thanks.