Water distribution housing leaking?

I just notice my port Engine water distribution housing is leaking by the plug tread, But I am wonder if it's one made in other material that this cheap plastic. The most expensive plastic in my engine $220. Thx

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Go Steelers!!!
Regards,
Ian
The Third “B”
Secretary, Ravena Coeymans Yacht Club
https://www.rcyachtclub.com/