You must be an old timer...yes, there were cast iron impellers years back and they used to slip when cold and then grip once you warmed up...eventually you had to change the water pump.
I pulled the water pump and it was a stamped impeller and after all those miles it was as tight as a new one in all planes and directions. Some of these 318 engines will go 300,000 miles and not even burn oil much less need a water pump. I revved my business vans with overloads like concrete forms, machinery, heavy tows etc. and they eventually had valve keeper and stem problems but this pickup has never been overly revved or abused engine wise.
