You can identify this pump by referring to the drawing. Note this impeller (#5) is accessed by removing a flat circular cover plate. The cover is secured to the pump body with six screws. The kit also includes gasket (#3)

Sherwood and Oberdorfer pumps were used interchangeably until August 1996 when Medalist Universal Motors was acquired by Westerbeke.

This pump was used on the engines listed below (and the boats that we are aware used these engines... There could be other combinations as well):
• M-12 (Catalina 25, Capri 26)
• M-2-12 (Catalina 25)
• 5411 (Catalina 27, Catalina 30)
• M-18 (Catalina 27, Catalina 30)
• M-25 (Catalina 30)
• M-25XP (Catalina 28, Catalina 30, Catalina 34, Catalina 36)
• M-320 (Catalina 27, Catalina 28, Catalina 30)
• M-35 (Catalina 34, Catalina 36, Catalina 38)
• 5424 (Catalina 38)
• M-50 (Catalina 42)

• Outside diameter (of a new impeller): 2-1/4"
• Width: 25/32"
• Inside diameter: 1/2"
• Number of blades: 12

This pump may have been replaced with the late model Sherwood pump by a previous owner. Earlier Universal diesel engines of most any model could have the newer pump as Universal provides an upgrade kit to replace older Sherwood or Oberdorfer pumps that have worn out. Compare your pump to the drawing to ensure you are ordering the correct impeller kit. If your pump doesn't look like this drawing, see the pump below under "May we also suggest" for the late Sherwood replacement pump impeller.