Sorry for the late reply, I haven't been on here in a long time.
I ended up changing the impeller which was quite the ordeal. The experience did allow me to fix a few things at the same time though.
The impeller replacement did involve removing the entire engine for me, including the bottom end, because the ISO ring had been improperly installed the last time the motor was out and was pinched so badly out of position on one side that the aluminum
casting was wearing away at the fiberglass
. So repairing that was a hidden blessing and only possible because I has a spare ring that I got with a reconditioned motor I have as a spare.
The impeller needed several trips to the dealer before I got the right one, but they had it in stock. Someone told me later that there are blue silicone replacements
available that have a greatly extended life. I was unable to find one.
I had the chance to repaint everything and reseal everything at the same time so that was a good thing too.
I think I burned the impeller out by testing the engine out of the water in the spring. I set up a tub and submerged the entire lower end in water before starting. I thought it would just draw it up and spit it out. I even saw water squirt out the exhaust. But if you watch for just a few seconds longer than I did, you'll find that was old water trapped in the exhaust/hoses that I saw spit out and the engine was now running dry because the impeller WILL NOT DRAW WATER UP THE LEG INTO THE ENGINE
. The actual engine must be below the waterline for it to draw water UNLESS you pressurize the source and force water up to the impeller. I didn't know this and that was the reason for needing one in the first place. Huge mistake. Stupid.
As for the future, I will do an automotive water-pump if I ever need to replace the impeller again. A friend tells me speed doesn't really matter and it changes with RMP only because it's driven by the motor itself. He says temperature is more important and that the thermostat could be used to trigger a relay to the pump, turning it on and off as required to maintain the right temp. (something like that..I forget exactly, but he said it would be simple).
One last thing...I still love this motor
Super dependable. Low maintenance
. Lots of power and always fires right up even without choke. Except for the stink of 2-stroke oil
...you couldn't ask for a better auxiliary.