Tom's father had instilled him an interest in how things work.
Should it be how things work or how things worked? It all happened in the past but "how things work" seems to be a general thing that Tom still is interested in today.
Did the fact that Tom is dead or alive make any difference in tense? Are there any difference in work/worked here? Or is one of them grammatically incorrect?
There's no "should" involved here. It's perfectly okay to use EITHER Present Tense work OR Simple Past worked in the cited context.
This is completely unaffected by whether the primary verb (instilled) stands alone as a Simple Past verb form, or is preceded by had to form a Past Perfect construction. Effectively, it's the same kind of optional "backshifting" that we often use in contexts like He said his name was Smith (as opposed to ...is Smith).
Note that "how things work" is really a "timeless" reference (unless context specifically points out that things have changed since then, which doesn't seem to apply to OP's question). So whereas with my Smith example we couldn't use Present Tense (...is Smith) if he'd since changed his name or died, there's no real sense in which that kind of restriction could apply to OP's example.
