Since no one else answered you, I'll take a crack at it. These instructions are for a 216, but I believe the 235 is the same.
- Remove rear bearing cap
- Remove old seal from groove and make sure groove is clean
- Insert new seal in groove with fingers
- Using a rounded tool, roll the seal into the groove
- Cut the small portion of the seal that protrudes from the groove flush with the surface of the bearing cap NOTE: To prevent the possibility of pulling seal out of groove a round block of wood the same diameter as the crankshaft flange may be used to hold packing firmly in place while the ends are being cut off
- If it should be necessary to replace the upper half of the seal, it will be necessary to remove the engine from the chassis and remove the crankshaft
- Replace cap and adjust bearing
Some guys have had a real hard time getting that seal to stop leaking, so make sure you buy a quality seal.
