Broken RV Water Pump

We like to visit our son in Arizona at least once a year. Last year was exciting because he and his fiancée got married at a beautiful outdoor wedding in late February. This year we are visiting again in February. We left home during balmy winter temperatures in the 50’s but drove all day to escape the approaching snowstorm. When we finally arrived in Bernadillo, New Mexico we were a day early so paid for two nights. There we found that the 12 volt water pump connected to the indoor water tank was not working. It tried to pump but just ran with no water going through.

Shurflo 4008 water pump
Shurflo 4008 water pump

The pump is known to have a problem with water flow when the internal check valve freezes so I disconnected it to see if it could be fixed.

DC power connection
DC power connection

The pump was held to the floor by 4 screws and connected to DC with a wiring clip so it was easy to remove.

Pump removed
Pump removed

Once it was out I watched a video describing the repair. There were eight screws that held the pump together.

Removed casing screws
Removed casing screws

It would have been easier to hold the pump to remove the screws with the filter taken off. But I didn’t realize that until I got into the disassembly.

Removed the filter attachment
Removed the filter attachment

The pump had three layers inside: the cover, the diaphragm and the casing.

Separating pump
Separating pump
Internal pump
Internal pump
Pump diaphragm
Pump diaphragm

As expected the check valve inside was stuck. But unlike the video I could not get the inner part loose. I removed the screws that held the part and popped off the check valve but I was unable to get the pieces apart.

Stuck checkvalve
Stuck check valve

I pounded on the inner part with a screwdriver and hammer and I found a plastic knob that fit so that I could distribute the force evenly to the inner part and hammered on that but it would not budge.

I even soaked the part in Pepsi hoping that the acid would dissolve whatever was holding it together but even that did not work.

Soaking checkvalve in Pepsi
Soaking check valve in Pepsi

We drove to Albuquerque to buy a new pump so we didn’t spend the second night at Bernadillo after all. We would be going in the wrong direction away from our route so we might as well keep on driving from Albuquerque. Instead we stopped at Caballo Lake near Las Cruces, New Mexico where I installed the new pump. I had to clip the old pump wires and connecting clip to install on the new pump. Fortunately Amazon carried the check valve for the 4008 pump for only $15. So I had it sent to my son’s house and I will be able to repair it and have a spare pump.

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