AMT 3941-96, Specifications Information And Repair Parts Manual, Page: 1 / 8

Specifications Information and Repair Parts Manual
3941-96, 3942-D6, 3943-96, 3944-96 & 3946-96
3941-252-00 1 6/2016
Please read and save this Repair Parts Manual. Read this manual and the General Operating Instructions carefully before attempting to assemble, install, operate
or maintain the product described. Protect yourself and others by observing all safety information. The Safety Instructions are contained in the General Operating
Instructions. Failure to comply with the safety instructions accompanying this product could result in personal injury and/or property damage! Retain instructions
for future reference. AMT reserves the right to discontinue any model or change specifications at any time without incurring any obligation.
©2016 AMT Pump Company, A Subsidiary of The Gorman-Rupp Company, All Rights Reserved.
Periodic maintenance and inspection is required on all pumps to ensure proper operation. Unit must be clear of debris and sediment. Inspect for leaks and loose bolts. Failure to do so
voids warranty.
3-Inch Trash Pump
Refer to form 1808-633-00 for General Operating and Safety Instructions.
MAINTENANCE
To prevent accidental starting, always remove the spark plug or
disconnect and ground the spark plug wire before attempting to service
or remove any component.
CLEANING
These units are designed so that for most cleanout or clogging problems it
should not be necessary to remove hoses or piping. The suction area and
impeller chambers can be reached by removing (2) threaded handles (Ref. No.
22), suction cleanout cover plate (Ref. No. 21) and gasket (Ref. No. 20).
NOTE: When replacing cleanout cover plate, carefully wipe clean all surfaces
on which the gasket has contact. Also, make sure the gasket is in position.
MECHANICAL SEAL REPLACEMENT
Refer to figures 1 and 2.
NOTE: Always replace the seal seat (Ref. No. 8), seal cartridge (Ref. N. 9),
and shaft sleeve (Ref. No. 10) to ensure proper mating of mechanical seal
components!
1. Unthread cap screws (Ref. No. 24) to remove casing (Ref. No. 19) and
casing seal (Ref. No. 7) from adapter (Ref. No. 9).
2. Unthread screws (Ref. No. 13) and remove volute (Ref. No. 14) from
adapter.
3. Unscrew impeller (Ref. No. 12) from the engine shaft. Remove the
impeller shims (Ref. No. 11), shaft sleeve and seal cartridge from engine
shaft. Use a rubber mallet or soft block of wood to loosen impeller. Turn
counterclockwise.
4. Unthread cap screws (Ref. No. 3) and remove the adapter from the engine
mounting face.
5. Push seal seat from the adapter recess with a screwdriver.
6. Clean the adapter 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 adapter. 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. (This
is a lapped surface and must be handled very carefully).
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 cracking rabbet on engine
mounting face.
13. Apply a light coating of soapy water to the inside rubber portion of seal
cartridge and slide onto the shaft sleeve. Slip the shaft sleeve with seal
cartridge onto the engine shaft.
IMPORTANT: Before installing new shaft sleeve, apply a bead of non-
hardening, pliable sealant (such as Permatex® Form-A-Gasket® No. 2) to
motor shaft shoulder.
14. Replace any impeller shim removed in disassembly.
15. Screw the impeller back in place tightening until it is seated against shims
and shaft sleeve.
16. Remount volute with fasteners.
17. Refer to section entitled SHIM ADJUSTMENT at this time if shaft sleeve
or any other parts listed therein have been replaced.
18. Inspect position of flapper valve assembly (Ref. No.15) to ensure proper
movement and seating.
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. Pump should
now run with renewed original performance.
SHIM ADJUSTMENT
1. When installing a replacement impeller, engine, shaft sleeve, adapter or
volute, it may be necessary to vary the number of impeller shims (Ref.
No. 11) that will be required. This is easily done by adding one 0.010”
shim more than was removed and reassembling pump as described in
Mechanical Seal Replacement section.
2. Ensure that volute (Ref. No. 14) and adapter (Ref. No. 4) are fitted firmly
(check fastener Ref. Nos. 3 & 13). Remove spark plug wire from engine
and turn engine over by pulling the recoil starter. If engine does not run
freely, disassemble pump and remove one shim.
3. Proper running clearance is 0.010”.
4. Follow the above procedure until proper clearance is obtained. This will
ensure maximum performance.
DESCRIPTION
These trash pumps are high capacity, heavy duty, centrifugal, engine driven, self-priming (to 20 ft. lift) portable units. The pumps are equipped with a precision
lapped mechanical seal to reduce leakage, carrying handle and a clog-resistant impeller capable of handling solids up to 1-1/2” diameter (up to 25% by volume).
A 3” NPT suction strainer is included. Handles liquids from 40º to 180º F (4º to 82º C). For use with nonflammable liquids compatible with pump component
materials.
NOTE:
Electric-start models require a 12-volt, 32 amp hour battery (not included).