Looking at a boat that has been sitting for 2 years. Impellers were replaced before the boat was put up. Okay to run them or should they be replaced?

depends on your luck,do you feel lucky,if not change them and go boating.

By looking at your location, I would back the boat in the water, leave it on the trailer, start the boat and see. I know guys that have the same impellers in their boat for 10 years. I scratch my head and think, why can't I be so lucky. I have also seen guys put new impellers in their boat every season. I have water pressure gauges for my motors and replace them when I see a drop in pressure. You can look at it as .. if it aint broke don't fix it. Or replace them now and not worry about it. But then it can be said why stop at the impellers? What about springs, rings... etc. Where do you stop?

If you gamble there is a slight chance they they could be brittle. Then you start the engine and parts of it break off and get lodged in always an orfice that is too small and hard to reach. Those always are expensive. Look at it this way the modest price to replace before you start can sure offer a huge piece of mind

3 pointstar

3 pointstar brings up a good point. So let me add that anytime you replace an impeller you should back flush your system. Even if all the impeller parts are there, other stuff can and does get caught in the coolers. I flush them by filling up the system with water, and with the hose off the sea pump, I use a special fitting I made, and blow about 80psi air through the system, forcing the water and air out. I do this a couple of times.

UnThat sounds like a good idea, where are you hooking the air up to?

At the end that connects to your cross over/thermostat housing. But make sure the other end (connecting to the sea pump) is disconnected. And by putting water in the system at the end that connects to the cross over/thermostat, with the air will unplug the honeycombs in the coolers. I made a 1.25 fitting with a on/off valve with an air chuck fitting that I just hose clamp into the end.

I must add that throughout the years of using my flushing tool/method, the junk& crud that comes out is unbelievable . I have had people come to me with issues that when they ran hard for any extended time, that their motor temps would start to climb a little. Well 99% of the time it was because of blockage in the system/coolers.

Change them, it's cheap insurance. I'd rather be boating than f'ing around getting a tow back and screwing with the back flushing hassle.

Cheaper to replace the rubber impeller, rather do that then scower the housing and have to replace the pump housing. Simple to do, one last maitinance item and you have a baseline