I had a PSS Seal replaced last year with the same type that serviced the boat for 18 years. This unit as per manufacture spec did not need water seal line from the raw water pump. What we found is on the Catalina 310 the shaft is right at the water line and the top of the seal may or may not get any water and will over heat and fail. What is now recommended is no matter what add a water line to the seal from the raw water pump. I was lucky as this was covered by the warranty parts and labor,