So sorry buddy, this project seems to be going south on you….
You are going to have to deal with the overheat situation now, before getting back to the original issues. I suppose it is possible that you just picked up a plastic bag which plugged this water intakes, but you really need to remove that gearcase now and have a look at the water pump. I am guessing this is a fresh water engine, so am hoping the driveshaft splines are not rusted into the crankshaft, which is somewhat common on these low profile engines. Nonetheless, you are going to have to look at the water pump before tending to the other issues.
Try loosening up the four bolts that retain the gearcase, if they come loose without much effort that is a good sign. Don’t force the screws if stuck, you don’t want to break them off. Once the four bolts are out, try prying the gearcase down just a bit. It will only come down about an inch or so due to the shift rod connector. The brass connector will be visible, remove one of the SS connector screws then the gearcase should come off.
Once the gearcase is off, there are four small SS screws that hold the aluminum impeller housing in place. Again, don’t force the screws, you don’t want to break them off. If all the screws come out without much of a fight, you can then lift off the impeller housing exposing the rubber impeller. Is the impeller in one piece? If so, perhaps the rubber part became dislodged from its brass/metal/plastic hub. You could be in BIG trouble if the impeller is broken in pieces.. If so, it is extremely important to find all the pieces (kind of reconstruct the impeller like they do after airline disasters). This is so important, because you want to confirm that no pieces of that impeller have been pushed up the water tube just waited to cause future issues that are near impossible to deal with.
So, let us know how you make out getting that gearcase off and inspecting the impeller. In the mean time, I will look to see if I have a 9.5hp service manual so I can figure out how that carb comes off there. Or, you can just remove the top of the carb to have a quick look inside. But be very careful, don’t drop anything down that carburetor throat..
OK, found a 68 OMC manual for the 9.5hp. It didn’t say anything about removing the flywheel, just said remove the five screws, there are only two on the back side of the carb. The manual did mention something about loosening/moving the “stabilizer bar”, whatever that is. You may need to make sure the throttle/magneto advance is completely retarded though, so that the two rear screws are exposed. Yes, I realize that your 64 model might be different than the 68 model that I read about, but I doubt it.
For now, let’s just have a look at the water pump, and worry about the carburetor later.
