The impeller on my 18hp Johnson has a bit of the impellerbalde broke off (the big en on one of the blades)<br />My dealer cant get me this part before 1.may,and I need the impeller tomorrow.
If i'm not wrong the impeller on anything over 10hp to 25hp in those year models will fit but i'm no expert. If you run the one with the broken blade keep a close eye on it if it comes apart it will overheat the motor real quick, as for you question yes it will cool your motor untill it comes apart.
That might work - it's got the same outside diameter and height right? The pre-'58 10hp used the same impeller as the later 18hp, just a different shaft size right?<br />It would probably be a good idea to fill up the extra space with something, so it doesn't wobble on the shaft.
I'm not sure like i say i'm not tech but i have swapped lower unit parts on a lot of the older motors and they worked, maybe not quite right but they worked.
it did not work. It pumped, but not enough, was so hot I almost burned my hand on the shaft. It seemed to work when it got cold,so I do not think i melted the pistons
