Thanks for your question! The cotter pins of the impeller broke, making it free to move up and down, thus crashing against the engine crankcase (in turn ruining the engine crankcase). Si ruppero le coppiglie della girante, rendendola libera di muoversi su e giù, andando così a rovinarsi contro il carter motore ( rovinando a sua volta il carter motore). For more info look at this video, "How to disassemble a Suzuki RG500 MK4 water pump" ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-h9pORzIqJ_8.html
Hi Stephen, thanks for your comment, very good question! We have tested this material (Nylon-carbon fiber) in water at 150 C° for 3 hours and no problems!!! And we empty all the engine from the water every time after used, so it's always dry. 👍👍👋👋