MEGA Corp. MMP4-2 User Manual
Page 31
 
MMP 4-2 
5 Nov 2011 
SECTION 5
Water Pump Assembly
5-8
20. Remove upper shaft seal and retainer (Item
26) by sliding off shaft. 
 
21. To remove impeller, shaft and lower seal,
use the following procedure: 
 
22. Remove snap ring (Item 17) from end of
impeller (Item 20). 
 
23. Push and hold drive end of shaft (Item 24)
toward discharge bowl (Item 22). 
 
24. Slide impeller back and remove split thrust
collar (Item 18) from shaft. 
 
25. Slide impeller forward to remove.
26. Remove shaft key (Item 19) and gently
slide shaft out of discharge bowl toward 
drive end. 
 
27. Inspect lower shaft seal (Item 21) and
replace if necessary. 
 
28. Inspect shaft and bronze discharge bowl
bushing (Item 10) and replace if worn. 
(Moderate wear [e.g: shiny areas or ridges 
not more than .010" (0.254 mm) deep] on 
shaft are acceptable, the upper bearing takes 
most of the loading). 
 
29. Inspect bushing (Item 12) in suction bowl 
(Item 13) and replace if worn. 
 
ASSEMBLY:
1. Assembly is performed in reverse order of
disassembly: 
 
2. Ensure O-Rings are properly installed in
grooves (Items 31 and 35). 
 
 
 
Use only clean grease when assembling 
new seal on shaft and when installing new 
seal seat in bearing housing. Apply a light 
film of clean oil to seal faces when 
assembling to prevent scratching surfaces. 
(Extreme care and cleanliness must be used 
when installing shaft seals to prevent 
possible component damage). Failure to 
keep items clean and use clean grease to 
perform this function may result in seal, 
bearing or shaft damage. 
 
 
 
The following is the required filling 
procedure for the bearing reservoirs when 
the pump is in a vertical position resting on 
the inlet end: 
 
3. Fill suction bowl bushing area to bottom of
bushing with waterproof grease. 
 
4. Fill oil hole (1/2" plug) in discharge bowl
(Item 22) to spill point (pump in vertical 
position) with clean hydraulic oil. Refer to 
line 5 above for oil specifications. 
 
5. Fill oil hole (1/4" plug) in upper bearing
housing (Item 7) to spill point with clean 
hydraulic oil. Refer to line 5 for above for 
oil specifications.