Yes, that is a carbon seal. You don’t need to split the case open to replace the O-ring inside the seal. While holding some downward tension on that spring, remove the C-clip around the base of the crankshaft. Under the C-clip is a small washer, followed by the spring, then a larger washer. Once the washers and springs are removed, carefully remove the black piece which is the carbon seal. Be careful with the carbon seal, as it can easily break. Inside the seal is an O-ring that needs to be replaced. Better yet, find a quad ring to replace the original O-ring. Assembly is the reverse of removal. Just be sure to hold downward tension on the spring so the various pieces don’t go flying all over the shop.

Edit – not sure on that model, but be sure to take special note of the orientation of the carbon seal when you remove it. Not exactly sure when the change was made but some models will have a raised lip on one side of the carbon seal – that raised lip side should face the crankcase. It almost looks like that black goo is the original sealer used to seal the case halves. At any rate, since you’ve already removed the powerhead, might as well replace the carbon seal O-ring.

• This reply was modified 4 years, 5 months ago by Bob Wight.
• This reply was modified 4 years, 5 months ago by Bob Wight.

Yes, it is a 1956. Look at your first (& other) pictures. See that drilled hole below the seal? If I am not mistaken, that is the dump for the crankcase puddle drains. A surprising amount of fuel/oil mix spritzes out that hole when running. That would account for the oil in the tower housing. It’s just the way they were back in “The Day”.

One of the o-rings in the parts book goes around the O.D. of the bearing. The case has to be split to access that one—-But don’t go that far. It is not an issue. The o-ring for inside the carbon has been superseded by a quad ring. By relying on memory only, I believe the part number is 305098. As for the carbon seal, it will be fine if it is not broken.

When you remove the snap ring, look closely and you will see one side has sharp edges, while the other side has slightly rounded edges. It goes with the sharp edges DOWN (toward you). Imagine the sharp edges digging into the crank groove. Upside down, it might pop off.