Quote:

The vanes can erode away and pump less.



I'm not saying that this is your problem, but it happened to me once. No usual warning signs -- no leaks from the weep-hole and no shaft-play. Finally pulled it, and the cupped portion of the vanes had completely worn away to the point that they weren't pumping at all, just spinning (the curve was completely gone). I used to have a picture of it somehwere...

Maybe check the temperature of the return hose to your radiator and see if it's hot/pumping... (it's not the most accurate, but I usually just use my hand and you can even feel when the thermostat opens).

1970 Dodge Coronet 1968 Barracuda FB 1970 Duster 1974 Dart 1977 Dodge Custom Van