Re: Which Impeller Kit? -- Alpha One with no Serial Number
This is one of those areas that gets opinions either way.... Generally, though, the O-ring is difficult to maneuver past the lower shaft seal in the upper drive, so much so that in alot of cases, the O-ring gets pushed out of the groove and then keeps the shaft seal from doing it's job of keeping water out of the spline area. Most people note that on disassembly, the old O-ring actually stays up in the splines and needs to be fished out. Last time I did my drive, I got lucky and was able to get the O-ring past the seal (lots of 2-4-c) and have had no problems. If you think about it, though, the drives past 1990 (i.e. Alpha I Gen II) do not even have the O-ring groove there anymore, but still use the two seals (one on the shaft below the splines, and one on the gear in the upper drive. O-ring not needed. Make sure you give a good dose of spline grease to those splines, though.
Another thing to consider: If you just drop the lower to change the impeller (and leave the upper on the boat), you dont have a good view of this shaft penetrating the lower seal in the upper drive during reassembly and have a bigger chance of the O-ring causing problems. If you join the halves on the bench, you have a birds-eye view of the shaft going into the seal and can ensure there are no problems. Just sayin'.
