01 YZ426 Cases Full of Oil?

I just pulled the top end off of a 01 426, and the oil was about to run out onto the floor. I know most of the oil should stay In the frame. Does the oil pump work as a 1 way check valve to hold the oil in the frame?

Not very well, no. The feed oil runs down to the right engine cover via the feed line, then across to the crankcase and up to the oil pump. From the pump, it goes back to the right engine cover, heading for the filter. There is a low pressure check ball at the point where oil exits the pump which is intended to hold oil in the tank (frame), but the pump itself has no seals on it anywhere, and given enough time with today's multi-grade oils, it will allow the entire contents of the tank to drain back to the crankcase.

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