When your impeller shreds does anything else in the water path usually get damaged. Took our boat out for the first time this year last weekend(I know a little late but new business is chaos) and upon idle out from the ramp the thing shot to 240 degrees so I shut it down. Inspected the hoses to find that they seemed sucked closed. Long story short 2 hours pass and some help from the wind get us close to the ramp so we load up for a disapointing first outing. Anyone that has experienced this please fill me in on what else I may need to check. Thanks for the help.
Small pieces can and will get caught in the thermostat. I shredded one about 3 years ago and pulled a stray piece out about 3 weeks ago... i typically change impellers at least every year or 50 hours whichever comes first. It may be overkill... but a $30 insurance policy (impeller) is peanuts compared to a new engine or a day lost on the water.
Sometimes large pieces can cause problems - no way to tell until you run it.
Change the impeller at the start of every year. Keep a spare on the boat with a new gasket set and tools for change out. Takes about 10 minutes on my Indmar. 30 minutes on a Merc.