1964 Fastwin 18hp long shaft Evinrude.. Just put the water pump impeller in and the housing screwed down tight. In the parts manual for the Evinrude Gear case group there is an O ring identified as part number 11in the 1964 parts diagram.. On the 1963 parts diagram it is identified as part #43. I have no idea what this O ring does or how it fits in the top of the water pump housing..There is no indentation for the O ring to sit in.. I just slid it down the drive shaft to the top of the pump housing. The top of the pump housing has "fins" in it so the O ring wont slide down any further than the top of the housing..., What the heck is this O ring for?? It does not appear to seal anything. It will just spin around on the drive shaft... I'm stumped !! don't want to finish putting this unit back together until I can find out what the heck that O ring is suppose to do..There is an indentation on the top of the drive shaft just under the splines but the diagram does not show the O ring in that place. .. Wisdom appreciated..
