Tech Wiki

Whale Gusher Galley Mk3 Service Kit

by Dan Cross, Ennui Went #159


The following are the steps I developed when installing service kits for my two Whale Gusher Galley Mk 3 foot pumps. These pumps have been manufactured since 1984, so I suspect they will be found on most all of our boats. The service kit is part number AK0553. It is widely available. I bought my kits on eBay. They looked like old stock, but the parts were fine. I have serviced two pumps, so I have limited experience. The following procedures worked for me. But, they may not all be correct (please mention any needed corrections) and certainly are not the sole way to accomplish this task.

Naming Parts

I found a pump exploded view with names for most of the kit parts. I could not find a view which names each pump part. So, I made up some part names to help with my description. My inventions are listed below and shown in Figure 1:

  • Pump body parts:
    • Front cover
    • Body
    • Rear cover
  • Piston parts:
    • Font piston plate
    • Piston
    • Rear piston plate
    • Piston bolt
    • Piston bolt O-ring/gasket
  • Valve assembly parts:
    • Valve body
    • Valve seat


  1. Remove four screws at pump lever. Keep these screws separate for reassembly. They are ¼” shorter than the front and rear cover screws. See Figure 2.
  2. Remove rear cover. Remove the six rear cover screws. Front and rear cover screws are the same size and can be co-mingled for reassembly. Pry the rear cover from the pump. The large O-rings on the valve bodies make pressure fits on the rear and front covers. See Figure 3.
  3. Remove valve assemblies. Remove the upper and lower valve assemblies. Set them aside for later disassembly.
  4. Remove rear diaphragm. Remove piston bolt, rear piston plate and piston bolt O-ring/gasket. The O-ring/gasket will be replaced and can be discarded. The diaphragm is likely pressed tightly to the piston and body. Pry the diaphragm loose from the piston with a small screwdriver, then pull the diaphragm away from the body. See Figure 4.
  5. Remove front cover and spring. The front cover is subject to spring force. Hold the pump down on your work surface or clamp the body and front cover together. Remove the front cover screws and the front cover from the body. Remove the spring. See Figure 5.
  6. Remove front diaphragm. Remove the front piston plate from the piston. Pry the front diaphragm from the body. The piston can be left in the body. There is no front or back to the piston. If it falls out during handling, it can be reinstalled in either direction.
  7. Disassemble Valves. Do the following to each valve assembly.
    1. Remove and discard large O-rings.
    2. Remove valve seat. The seat can be tapped out from the opposite end of the valve body. It is held in the valve body by the small O-ring. Figure 6 shows one method, with the valve body placed in a vise and a cut and squared off 10d nail used to reach the valve seat. A vise may not be needed. A strong grip and a small screwdriver will likely also work.
    3. Remove valve seat small O-ring and discard.
    4. Remove valve stems and valves and discard. The valve stems can be pulled out with pliers and pushed in from the outside of the outflow valve.


See the Observations at end of this article to change pump from right to left hand or to change the valve intake position from bottom to top.

  1. Reassemble intake valve. The intake valve has the valves and valve stems on the outside of the valve body. See Figure 11. There is no difference in the two valve bodies. Either can be reassembled as the intake or outflow valve. In both valve assemblies, the concave surface of each valve is installed facing the concave surface of the valve body or valve seat, so that the surfaces meet as shown in Figure 7.
    1. Reseat valve seat. Place new small O-ring on valve seat. Orient valve seat so that the concave side will face outward. Apply dish soap to O-ring. Press valve seat into valve body. You can’t go too far. There is a ledge in the valve body that stops the seat.
    2. Install new valves and valve stems. The valves’ concave sides will face inward towards the valve body/seat.
    3. Install new large O-rings on valve body. They are slid up next to the step in the valve body.
  2. Reassemble outflow valve. The outflow valve has valves and valve stems on the inside of the valve body. See Figure 11.
    1. Install new valve and valve stem to inside of valve body. Valve’s concave side will face outward to meet the valve body. I propped the valve and valve stem on the intake valve body nipple, see Figure 8, to get the valve/stem assembly into valve body. Needle nose pliers may also work.
    2. Install new valve and valve stem to remaining valve seat. Again, the valve’s concave surface faces the concave surface of valve seat.
    3. Reseat valve seat. Place new small O-ring on valve seat. Apply dish soap to O-ring. Press seat into valve body with the valve on the inside of the valve body.
  3. Reassemble front diaphragm. First, a note on diaphragm orientation. The diaphragms are identical. Either can be used for the front or back. Each diaphragm is installed with its concave surface facing outward toward its cover. Just in case your diaphragm is inverted, the raised inner and out rims are on the convex side of the diaphragm.
    1. Insert front piston plate into new front diaphragm. Concave side of the diaphragm will face towards the front cover.
    2. Slide front piston plate into piston (which should be in the body). See Figure 9.
  4. Reassemble rear diaphragm. Insert piston bolt through rear piston plate. Install piston O-ring on inner side of rear piston plate. Center rear diaphragm on the rear piston plate, with the concave surface of the diaphragm facing towards the rear cover. Screw the rear diaphragm assembly to the piston assembly with the piston bolt. See Figure 10.
  5. Reattach rear cover.
    1. Press the rim of the rear diaphragm into the body. First, press the diaphragm in by hand pressing down and inwards toward the center of the diaphragm. Do not press and slide along the outer rim, which can stretch the rim of the diaphragm. Press the rim again with a flat surface, for example, a wide flat screwdriver.
    2. Reattach the rear cover to the body with the rear cover screws.
  6. Reinstall valve bodies to rear cover. Apply dish soap to the large O-rings on the valve assemblies. Insert the intake valve assembly (valves on the outside of the valve body) to the bottom valve cavity in the rear cover. Insert the outflow valve assembly (valves on the inside of the valve body) to the upper valve cavity. See Figures 11 and 12.
  7. Reattach front cover.
    1. Press the front diaphragm into the body, using the techniques outlined above for the rear diaphragm.
    2. Insert the spring in the front piston plate. See Figure 12.
    3. Reattach the front cover. Again, the front cover will be subject to spring force. First insert the front cover screws into the front cover. Line up the cover to the body and valve assemblies. Press down on the body against your work surface and screw down the screws. The front cover will pull down onto the valve assemblies as the screws are tightened. See Figure 13.
  8. Reinstall the four screws at pump lever.


I was impressed by the quality and design of these pumps. I can see why they have remained unchanged for 30 years. The only damage I found looks to be related to anti-freeze. I found a pink “high water” line in the pump attached to the refrigerator box. I suspect the line was created by anti-freeze left in the pump each winter. The lower intake valves in this pump were deformed. I don’t know for certain, but suspect that the damage is from the anti-freeze. The pump still worked, but it seemed to take a lot of strokes to clear the refrigerator box.

Changing Orientations

Right to Left Hand. My pumps are right handed. The front and rear covers appear to be mirror images. I suspect the pump hand can be changed from right to left by simply swapping the front and rear covers.

Intake and Outflow. The intake on each of my pumps is at the bottom. It appears that the intakes can be changed from bottom to top by simply switching the positions of the intake and outflow valve assemblies.

Figure 1