I went out for a ski yesterday and experienced an "interesting" situation with my impeller. During a run, the engine sound changed pitch and on investigation I decided the impeller had probably blown. The check engine light was flashing and the temperature gauge was hovering at 200 or a bit below - definitely was not topped out. We limped back to the dock and the temp didn't go up further but didn't go down either.

Today, I removed the impeller and was expecting broken fins - no breaks - the impeller really looked very good. Just for grins, I decided to turn the engine over with the cap to the water pump off. The impeller would start to spin but then it stopped ... several times. When I went to the dealer, he initially told me there was nothing wrong with the impeller. When I told him about the lack of spin, he determined that the inner metal hub had broken loose from the rubber - it was still too tight to turn by hand but ... My dealer said that he had only seen the same thing happen once before - early last spring on a brand new (just out of shrink wrap) Malibu.

Anyway, if your engine seems to have blown an impeller but the impeller looks good, check to see if the hub broke loose ... don't assume it is OK.