If the water pump housing is aluminum (ugh) I would put some gasket sealer between the cup and the housing. Corrosion was known to build up between the housing and cup, causing the pump to stop working, due to metal distortion. If the housing is plastic, nothing is needed. That’s why they went to plastic. It is one case where plastic is actually way BETTER than metal.* As for the gaskets, I like to put a light coating of engine oil or grease on them. This will allow it to be taken apart down the road for a quick inspection if needed, without destroying the gaskets. Do not go overboard on this, just a very light coating. Impellers don’t like grease and oil.
*The downside to plastic housings is that they cannot dissipate heat very well. So if you were to start the engine with no water supplied, the impeller would start to be heat damaged in as little as three seconds.
Long live American manufacturing!
