Gorman-Rupp Pumps 16C20-F4L 1317844 and up - Manual (Page 36)

10 SERIES OM-01604
MAINTENANCE & REPAIR PAGE E - 14
The shaft and impeller threads must be
completely clean before reinstalling the im­
peller. Even the slightest amount of dirt on
the threads can cause the impeller to seize
to the shaft, making future removal difficult
or impossible without damage to the im­
peller or shaft.
Install the same thickness of impeller adjusting
shims (32) as previously removed, and screw the
impeller (2) onto the shaft until tight.
NOTE
At the slightest sign of binding, immediately back
the impeller off, and check the threads for dirt. Do
not try to force the impeller onto the shaft.
A clearance of .025 to .040 inch (0,64 to 1,02 mm)
between the impeller and the seal plate is neces­
sary for maximum pump efficiency. Measure this
clearance, and add or remove impeller adjusting
shims as required.
Remove the two capscrews temporarily holding
the seal plate, and install the same thickness of
casing gaskets (55) as previously removed. Se­
cure the seal plate and pump casing to the inter­
mediate with the nuts (16). Do not fully tighten the
nuts until the impeller face clearance has been set.
NOTE
If the pump has been completely disassembled, it
is recommended that the wear plate (57) and back
cover assembly (62) be reinstalled at this point. The
back cover and wear plate must be in place to ad­
just the impeller face clearance.
A clearance of .010 to .020 inch (0,25 to 0,51 mm)
between the impeller and the wear plate is also rec­
ommended for maximum pump efficiency. This
clearance must be set after installing the back
cover, by adding or removing gaskets in the pump
casing gasket set (55) until the impeller scrapes
against the wear plate when the shaft is turned. Af­
ter the impeller scrapes, add approximately .010
inch (0,25 mm) of gaskets.
NOTE
An alternate method of adjusting this clearance is to
reach through the discharge port with a feeler
gauge and measure the gap. Add or subtract pump
casing gaskets accordingly.
If a lifting eye was used to move the pump casing,
be sure to remove the lifting eye from the pump
casing.
Do not attempt to lift the complete pump
unit using the lifting eye. It is designed
to facilitate removal or installation of in­
dividual components only. Additional
weight may result in damage to the
pump or failure of the eye bolt.
Suction Check Valve Installation
(Figure 2)
Inspect the check valve assembly (79), and re­
place it if badly worn.
NOTE
The check valve assembly must be replaced as a
complete unit. Individual parts are not sold sepa­
rately.
Replace the seat gasket (70) and secure the check
valve seat (71) to the pump casing with the round
head machine screws (72).
NOTE
If the suction flange or check valve seat was re­
moved, replace the respective gaskets, and apply
`Permatex Aviation No. 3 Form‐A‐Gasket' or equiva­
lent compound to the mating surfaces.
Reach through the back cover opening with the as­
sembled check valve, and position the check valve
adaptor in the mounting slot in the check valve
seat. Align the adaptor with the seat hole, and se­
cure the assembly with the check valve pin (80).
Replace the suction flange gasket (73). Secure the
suction flange (76) to the check valve seat and
pump casing with the hardware (74 and 75).