After hearing a noise I disassembled the water pump and found that the impeller had come off the shaft. Nothing appeared damaged so I tapped it back on, reassembled is things worked for a while but the noise returned, ie., the impeller came off again. I'm trying to figure out how the impeller is suppose to attach to the shaft. It has a place for the shaft end to press into (a large hex nut opening). Is it suppose to be a press fit? If so how do I keep it from coming off again - tapping it securely in didn't work? Epoxy of some type? Or do I have to buy a new impeller, in which case, I still have the same question... how would it attach to the shaft? Here's the pump assy I'm dealing with... http://www.jbparts.com/jbr0010.html Thanks Mike

The impeller should actually thread/screw onto the motor shaft. The "hex end" that you are talking about is probably the nut that was originally molded into the impeller. It sounds like the impeller either got hot and melted or broke its way free at some point.

If there has been any water leaking onto the motor shaft the nut will most likely need some persuasion to remove. If none of the other pieces of the wet end have been damaged by the impeller coming free and you can find somewhere to get it you can probably just order a new impeller and install it. Replace the shaft seal assembly at the same time. If you can't find just the impeller you will need to replace the entire wet-end with something of a similar rating and configuration.

A good walk through of a seal replacement procedure with pictures is available HERE. That includes disassembly and reassembly showing how the impeller threads on and off and what to do if the impeller is "frozen" onto the shaft and breaks when you try to remove it.

Your impeller's threads are probably stripped. You'll need a new one.

I'm still trying to understand how the impeller should attach to the pump shaft. I don't see any threads at the end of the shaft, or on the impeller. I don't have a picture of the shaft but can describe it. The end is hex shaped, all metal, no threads. It fit into the center of the impeller which had a matching hex shaped opening, no threads. I thought the threaded part may have been stuck in the impeller so I tried heating it up but realized it's all plastic and started to melt. Attached is a picture after it melted a bit. Still, no signs of threads. I obviously need to buy a new impeller at this point but would like to know how it ends up attached to a shaft with no threads. Perhaps there's a missing piece? Or, this Pirahna A pump is different then most? Here's what I have again... http://www.jbparts.com/jbr0010.html Thanks in advance for any suggestions. Mike

What you are seeing on the end of your motor shaft is the brass thread insert that is molded into the impeller when it's made. It broke loose, hence your impeller not staying on anymore.

Can you elaborate a little more so I know what part(s) to buy? Do I just buy another impeller?

Once you've gotten it removed from the motor shaft all you'll need is the new impeller.

I tried to find these directions posted in this thread, http://spasupport.com/seq/werep/afpsrep1.html, but seems the website is DOA now, did anybody make a pdf file of the instructions?

This was planned. Everything has been moved to: http://sparesources.com/seq/werep/afpsrep1.html