IO impeller pump replacement interval?

[Euroski]

A friend has typical mercury IO/V6 and would like to know when the impeller should be replaced per the Merc manual.

[samari]

3 years is a good average from what we see, but that's up here in MN

[vnemous]

we recommend a cooling system service every three years especially if the area you boat in is sandy and shallow.

[rgsauger]

Down south where the seasons are much longer, we do ours at least every two years. I have seen them in real need of replacement at the 2 yr mark. It's not hard at all on that rig. You have to drop the lower unit but it's only 6 or 8 fasteners - I forget which.

[flabum1017]

I do all impellers every year, cheap insurance

[lokinutz]

Just swapped out impellers on an '04 volvo/penta 5.7 I/O. First time it had ever had water pump, drive oil, or ANY other maintenance done, except battery change. Don't think i would go 8 years. 8 years. REALLY?? 8 years.