I did a water pump on an 1980 D150 a few months ago. It was the original pump as the truck had 15,000 miles on it. The other day the owner complained of it over heating and suspected the pump, I bought a new one and checked the truck out. It ended up being a semi plugged radiator but I pulled the pump anyway and changed it. While I had it off I noticed the impeller is opposite to the one I removed which also matched the factory original I removed previously. Which one is right or does it even matter?

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

It does not matter; there is no "backwards".

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Maybe it is from a marine or industrial application or maybe the rebuilder messed up.

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63 Plymouth Valiant Wagon

It is not from a marine or industrial application. The rebuilder did not mess up. There is nothing about the new water pump's impeller that will make it any less effective than the old pump's impeller.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

...read the link above in Ed's reply, it explains impeller design pretty thoroughly.

Brian

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https://tinyurl.com/yynpj4v2