Welcome to the Forum!

A crack in the body of the valve means it's gotta be replaced or 'band-aided' Do you know the brand of the valve? - Jandy valves come with a life time guarantee.

If replacing the valve isn't an option, I can tell yo how to properly epoxy putty it. If you want to replace the valve, I can give you a few tips on 'playing' with PVC piping.