10
Replacing Pump Stack
For Reference Numbers [shown as (3) or (5)], refer to
the Exploded View, Figure 14 for the BVM2 and BVM4
Series Models and Figure 15 for BVM8 and BVM16
Series Models.
Risk of explosion and scalding. Do not run
pump with discharge valve closed; the water in the pump
may boil, causing risk of explosion and steam burns to
anyone nearby.
1. Follow steps 1-8 under Motor Replacement, then
proceed with step 2 below.
2. Remove the four staybolt nuts, flatwashers, and
lockwashers (7, 8, and 9) from the staybolts (19).
NOTICE: It is not necessary to remove the staybolts
when replacing the stack.
3. Lift the motor bracket (6) off of the pump body.
NOTICE: Note the position of the priming plug. The
priming plug must be returned to its original position
during reassembly.
4. Remove and discard upper sleeve O-ring* (17).
5. Clean gasket seat.
6. Remove and replace round spring ring (BVM2 and
BVM4) or conic spring (BVM8 and BVM16) (14).
7. Pull the old stack (16A through 16L) out of the
stainless steel sleeve (18) by pulling straight up on
the pump shaft (16A).
8. Remove the stainless steel sleeve (18).
9. Remove and discard the bottom sleeve O-ring* (17).
10. Clean the O-ring seat.
11. Remove and discard the O-Ring* (21A) from the
suction/discharge (21 - BVM2 and BVM4 only).
12. Cast Iron Models Only: Clean the O-Ring seat and
install a new O-Ring (21A).
13. Install a new lower sleeve O-ring*.
14. Install the new stack without the stainless
steel sleeve.
NOTICE: Be sure to align either the small priming
hole or the suction interconnector pin hole (located
on the bottom stage of the stack) properly in the base
of the Suction/Discharge (21). See Figure 12 (not
necessary on BVMI/X models).
* Or, on some older models, a paper gasket.
NOTICE: If the pump was originally built with a
splined shaft and is being replaced with a dual
flat shaft, there is a specal adapter bowl included
in the Replacement Stack kit that is to be installed
above the suction interconnector and below the
replacement stack. If not needed, this adapter bowl
may be discarded.
15. Use a rubber mallet to tap the stainless steel sleeve
(18) into place.
16. Install a new mechanical shaft seal (15A and 15B).
Refer to Replacing Mechanical Seal.
17. Install a new upper sleeve O-ring* (17).
18. Install a new round spring ring or conic spring (14).
19. Reinstall the motor bracket (6) on the pump body.
Align the priming plug (10) to its original position.
20. Oil the threads on the staybolts (19).
21. Replace the lockwashers, flatwashers, and staybolt
nuts (7, 8 and 9) and cross-torque the staybolts. See
Table VIII for torque specifications.
22. Reinstall the motor (1) on the motor bracket (6) and
turn the motor to the desired terminal box position.
23. Follow steps 10 - 21 under Motor Replacement. You
have now finished changing out the impeller stack.
Priming
Hole
Housing
Knob
Suction
Interconnector
Interconnector
Pin
Suction/Discharge
Figure 12 - BVM2, BVM4 – Align Small Priming Port.
BVM8, BVM16 – Align Interconnector Pin.
No alignment is necessary on BVMI/X models.