Rebuilding
the
Welch 1402
Vacuum Pump

Cleaning

(Revised)

C1

Clean the intake rotor, first remove the large vanes, then remove the spring holders, they go through holes in the shaft, then remove the intake rotor from the shaft.

C2

Shown are the disassembled parts, the springs and the woodruff key are easy to misplace.

C3

Clean the springs with the pipe cleaner and the toothbrush.

C4

Clean the hole in the large vanes with the pipe cleaner, inspect the surface of the vane that contacts the cylinder, if there is scoring please replace the vanes.

C5

If the springs are missing or damaged or the intake spring holder is bent, please replace them with new parts. Replacing this entire assembly regardless of wear could be a great investment please check the prices.

C6

Clean the intake rotor with the scrubby pad, do not clean it with anything that might scratch the metal, clean the holes and the 2 channels in the intake rotor.

C7

When the parts are clean, reassemble by putting the intake spring holders into the intake rotor, putting on the 4 springs and then putting on the large vanes.

C8

Reassembled intake rotor.

C9

By gently pressing on the vanes they should move back and forth freely, if not, replace parts. When installed the vanes should always be in contact with the cylinder walls as the shaft turns. This is how the vacuum is created.

C10

Disassemble the intake rotor and reassemble it on the shaft, repeat the above procedure for the exhaust rotor.

C11

Clean the intake ring and valve assembly.

C12

Clean both vacuum intakes.

C13

Close-up of the vacuum intakes.

C14

Remove the baffle plate.

C15

Remove the valve assembly and clean the parts, any parts that cannot be cleaned or are damaged should be replaced with new parts, be sure to clean the area on the baffle plate under and around the valve assembly so there is a good seal between the valve assembly and the baffle plate. Please consider replacing the springs regardless of wear, check prices.

C16

Clean the center plate.

C17

Clean the openings in the center plate with a cloth passed between the two openings.

C18

Clean the exhaust ring.

C19

Clean the lower and upper exhaust valves on the exhaust ring.

C20

Disassemble the lower and upper exhaust valves on the exhaust ring, clean the opening with the pipe cleaner, replace damaged or broken parts with new parts. If the metal strips are worn, damaged, rusted or cannot be cleaned please replace them.

C21

Clean the end plate.

C21.1

Clean all of the openings in the end plate, clean the small channel in the opening for the shaft.

C22

Soak the oil case assembly in a bucket of mild degreaser for 24 hours to loosen the deposits and make it easier to clean.

C22.1

Clean the oil case assembly.

C23

Remove the window covers on each side of the oil case assembly.

C24

Remove the glass window assembly, clean the glass being CAREFUL not to scratch the glass with whatever you are cleaning it with, clean the openings in the oil case assembly with a pipe cleaner. The o-ring should be replaced with a new o-ring.

C25

Remove the drain valve assembly. A small piece of PVC pipe put on one end gives you more leverage and makes it easier to turn.

C26

Use a pipe cleaner to clean the openings in the oil case assembly and the drain valve.

If the drain valve was leaking oil please replace it with a new part.

C27

When re-installing the drain valve put a small amount of thread sealant on the threads.

You can get thread sealant at NAPA auto parts.

C28

Sample thread sealant.