How To Maintain An Oil Pump

Disassembly:
a. Remove the coupling and the pressure plate assembly.
b. Remove the pump housing.
c. Remove the impeller: First, use a wrench to remove the impeller nut (for the forward pump, the nut is reverse-threaded; for the reverse pump, it is forward-threaded). Then, use a pulling tool or a slant iron to withdraw the impeller.
d. Remove the shaft seal components (including the mechanical seal pump cover, seals, etc.).
e. Remove the moving ring of the mechanical seal.
f. Withdraw all the seals such as the static ring of the mechanical seal, packing, etc. from the sealing cavity.
g. Remove the debris ring, etc.
h. Withdraw the shaft sleeve. If the shaft sleeve is too tight, use a wedge block to strike its tail (at the shaft shoulder) to make it loose.
i. Remove the two bearing covers.
j. Remove the locking nut and locking gasket or clamp ring. If there is a bearing seat, pull out the bearing seat.
k. Remove the shaft and bearing components from the pump base (note: do not damage the shaft shoulder).
B. Check
a. Impeller: If there is severe cavitation (especially for the main blades), excessive corrosion, erosion, or damage, the impeller must be replaced.
b. Shaft: If the radial runout exceeds 0.05mm, the oil seal position is severely scratched, or the threads, grooves, steps, and other surfaces on the shaft are damaged, the shaft must be repaired. If repair is not possible, the shaft must be replaced.
c. Shaft sleeve: If the surface is rough and severely damaged, the shaft sleeve must be replaced.
d. Oil seal: The disassembled oil seal must be replaced.
e. Bearing: For excessively worn bearings, those that are too tight, too loose during operation, or noisy must be replaced (new bearings can only be opened when replaced, and the replaced bearings must be of the same model and size as the original bearings of the pump).
f. O-ring seal: Generally, the disassembled O-ring seal should be replaced. For other sealing gaskets and pads, as long as they are not damaged, they can be reused.
g. Mechanical seal: Check the sealing surfaces of the dynamic and static rings of the mechanical seal. If there is obvious damage, the mechanical seal must be replaced.
C. Assembly (refer to the structural diagram)
The assembly sequence should be carried out in the reverse direction of disassembly.
a. All parts must be cleaned before assembly, especially the threads, bearings, and lubrication parts of the bearings. They should be cleaned carefully, and some rough parts should be polished with fine sandpaper.
b. First, install the bearing at the power end, attach the retaining ring or tighten the locking nut to hold the locking gasket, and the tightening torque of the locking nut: 346 Newton-meters. If there is a bearing seat, install the bearing seat into the pump base first, then install the shaft with the bearing, install the power end bearing cover, install the coupling; then install the other end bearing and press the bearing cover.
c. When installing the shaft sleeve, apply a thin layer of anti-wear agent on the shaft, and install the mud ring.
d. Install the pump cover with the mechanical seal (the static and dynamic rings of the mechanical seal should be installed first).
e. Put the mechanical seal dynamic ring on the impeller, install the impeller, and the gap between the back of the impeller and the pump cover should be 0.7 - 1mm. Tighten the impeller nut with a special wrench.
f. Install the pump casing.
g. Install the pressure plate assembly, adjust the tightness appropriately, do not tighten too much, otherwise, the packing may be burned during pump operation.
h. At each assembly step, check whether the sealing gaskets, oil seals, O-ring seals, etc. are installed properly; after assembly, rotate the shaft by hand to ensure it is flexible, and there should be no jamming in any part.