Quick question - impeller replacement PCM GT40

[ally505]

A couple of quick questions.

The impeller has seen about 3 hrs use but has sat in the housing for 2 years so has taken a set, assume it would be best to ditch it and replace. Second question, the new impeller came with an o-ring however when, from memory, the last time I disassembed the pump, there wasn't one there. On reassembly does the o-ring go on the shaft before the impeller or after? Thanks
I'

[hyparks]

The only O ring I'm aware of for the gt40 pump is the one that sits between the impellar housing and the brass plate. It's quite a big one so wouldn't fit on the shaft.
Rebuilt my entire pump a couple of weeks back.

[Chexi]

Definitely replace that impeller. You should pull your impeller after the riding season (every time). If at the beginning of the next riding season it still looks like new, you can use it again. Better to buy a new one though and use it, saving last year's as an emergency spare. It's cheap insurance.