Impeller replacement interval

[jlblau]

How often does everyone replace their water pump impellers? Is it more a function of running hours or time between change outs?

 

[ribfan]

I just did mine at 200 hours. The old impeller looked ok, and the water stream was ok as well, but it was time. Some guys replace sooner, I guess it can depend how you use the motor and if it sucks mud or sand on a regular basis. When you do the impeller you should also consider changing the two thermostats. They were looking pretty crusty, so I'm glad I replaced them.

 

[chawk_man]

I run in saltwater and need to occasionally kick up mud getting on and off my dock at low tides. So I change mine every 200 hours, which equates to every year for my usage level.

 

[jgmo]

I work on the smaller outboards but will tell you that I frequently take out impellers that have over three years on them and are still pumping but some are in pretty bad shape. I recently did one that only had one full arm left on the impeller along with two long "stubs" and it was pumping and pissing a stream. If you let them go that long, you can never be sure where all the pieces went either.
I usually recommend every other season unless you are like chawk_man and are kicking up the bottom alot. Doing the thermostats every other season is also a good practice as it gives you the opportunity to see in the cylinder head water passages and, as jiblau said, it can get pretty crusty in there. There are some associated anodes or zincs in those cavities that I would also advise you to change for some cheap insurance.