27
n
n
Reassembly
Reassemble the pump by reversing the order of disassembly. Take care not to contaminate or damage the seal
faces for o-rings. Tighten bolts uniformly to prevent uneven tightening.
1. Place the drive magnet assembly onto the motor shaft.
• For MDH-400/401/422/423 models
Motor shaft should be flush with the drive magnet boss. Secure drive magnet to motor shaft with two
set screws. Apply Loctite 242 (or equal) to both set screws. Check that there is no foreign matter
adhering to magnets.
• For MDH-(F)425 models
Place drive magnet assembly onto motor shaft with two set screws. Mount motor bracket with base
plate side down onto motor face. Adjust position of drive magnet on motor shaft such that it measures
1/10" below the face of the motor bracket (see figure below). After magnet set height is correct, tighten
two set screws to secure magnet to motor shaft.
• For MDH-(F)422/423/425 models
Screw the impeller clockwise onto the magnet capsule assembly, hand tighten. Secure magnet capsule
and tighten impeller the rest of the way using a strap wrench. Should the impeller be hard to screw on,
place magnet capule in hot water (approx. 194°F 90°C) for five minutes, then assemble. Gap between
rear shroud of impeller and top of magnet capsule should be less than 0.020".
4. Check that there is no foreign matter adhering to magnet capsule assembly.
5. Slowly insert magnet capsule assembly with bearing, impeller and mouth ring into rear casing.
Caution Watch fingers! (Strong magnets)
6. Check that there is no dust or defects on the seal faces of front casing and rear casing.
7. Place O-ring into front casing.
8. Mount front casing with O-ring onto rear casing.
1 /1 0 "
F o o t
su p p o rt
D rive m a g n e t
M o to r
sh a ft
1 /8 "
!
2. Insert rear casing into motor bracket. For MDH-
F425, slide retaining ring onto rear casing, and then
insert rear casing into motor bracket.
3. Install impeller to magnet capsule assembly.
• For MDH-(F)400/401 models
Align the impeller and magnet capsule, and
with an arbor press, press the impeller into the
magnet capsule assembly. Note: Use a flat sur-
face material greater than the mouth ring for proper
alignment. Should the impeller be hard to insert,
place magnet capsule in hot water (approx. 194°F,
90°C) for five minutes, then assemble impeller to
magnet capsule assembly.
