After replacing the head on the Ninja, and changing the oil 3 times I was still finding lost coolant in the oil. I’d checked the troubleshooting list in my Haynes manual, but all it listed was the head gasket/head, but the bike starts right up and has good compression with no evidence of head gasket failure, so it must be something else.
Enter the good old intarwebs. While looking at the diagrams on BikeBandit I found out that the water pump plugs into the crankcase.
Yes, the bearings and internal seals failed allowing the impeller to bounce around like crazy and push coolant into the crankcase. I guess its a good thing that I’ve changed the oil three times and the filter twice. I’ve probably collected most of the aluminum shavings from that last ride when it failed.
I ordered one off ebay for $25 that is supposed to work as I can’t find a rebuild kit for it.