AMT 1640-163-94 Mechanical Seal - Viton/Carbon/Silicon Carbide Type 21

The AMT 1640-163-94 is a Mechanical Seal, Viton/Carbon/Silicon Carbide, Type 21, size 1-1/8 Inch for an AMT Pump. MECHANICAL SEAL REPLACEMENT
Always replace the seal seat , seal head and shaft sleeve to ensure proper mating of mechanical seal components! See Figure 1 1. Unthread cap screws and remove casing and casing seal from casing cover . 2. Unthread screws and remove volute from casing cover. 3. Unscrew impeller from the engine shaft. Remove the impeller shim , shaft sleeve and seal head from engine shaft. Use a rubber mallet or soft block of wood to loosen impeller. Turn it counterclockwise. Disconnect spark plug wire and battery to prevent accidental starting. 4. Unthread cap screws and remove the adapter and casing cover from the engine mounting face. 5. Push seal seat from the casing cover recess with a screwdriver. 6. Clean the casing cover recess before inserting a new seal seat. 7. Carefully wipe the polished surface of the new seal seat with a clean cloth. 8. Wet the rubber portion of the seal seat with a light coating of soapy water. 9. Press the new seal seat squarely into the cavity in the casing cover. If the seal seat does not press squarely into the cavity, it can be adjusted in place by pushing on it with a piece of pipe. Always use a piece of cardboard between the pipe and the seal seat to avoid scratching the seal seat. . 10. After the seal seat is in place, ensure that it is clean and has not been marred. 11. Using a clean cloth, wipe the shaft and make certain that it is perfectly clean. 12. Secure the adapter on the engine mounting face. NOTE: Tighten cap screws EVENLY to avoid cocking rabbet on engine mounting face. 13. Apply a light coating of soapy water to the inside rubber portion of seal head and slide onto the shaft sleeve. Slip the shaft sleeve with seal head onto the engine shaft. IMPORTANT: Before installing new shaft sleeve, apply a bead of non hardening, pliable sealant around motor shaft shoulder. Do not touch or wipe the face of the polished part of the seal head. 14. Replace any impeller shims removed in disassembly. 15. Screw the impeller back in place tightening until it is seated against shims and shaft sleeve. NOTE: Check to be sure that the shaft sleeve is in place against engine shaft shoulder. Model 3993-96 requires a shaft flange . 16. Remount volute with fasteners. 17. Refer to section titled Shim Adjustment at this time if shaft sleeve or any other parts listed therein have been replaced. 18. Inspect position of flapper valve assembly to ensure proper movement and sealing. 19. Replace o-ring seal on volute rabbet. NOTE: Always inspect o-ring seals. Replace when cracked or worn. Wet o-ring with soapy water for ease of assembly. 20. Remount casing. 21. Remount any other parts and reconnect spark plug wire and battery . Pump should now run with renewed original performance.