Engines become really loud

[Immortality]

Noisy tappets are normally referring to the lifters. It's common enough and most people replace them but I think it's probably a push rod problem simply because with a roller lifter like the V6 has the lifter/push rod don't rotate like they do on the older flat tappet style cam. A spinning push rod has much less chance of wearing into a rocker arm.

If the lifters themselves are noisy you could try a bottle of Nylon Lifter Free. It works very much like an engine flush but it doesn't thin out the oil so you can add it and leave it in. It is a great way to clear carbon out of the engine but it will make you clean oil go black (just shows it's doing it's job). Lifters have the smallest internal orifices of any part of the engine so if there is any crap floating around the engine it is most likely to get caught in the lifter creating oil flow issues (through the lifter) leading to a noisy lifter.

Our VX has a good service history and yet when I did the high ratio rockers 10/12 push rods were worn on the rocker end. Engine has been much quieter since.

 

[greenacc]

It's a timing chain on Commodores. Yes Noisy tappets pretty much includes all three parts you listed. You've just got to work out what's worn the most.
In an overhead cam engine the tappets are often adjustable (or were on older engines) and would make a horrible rat tat tat sound when out of adjustment. That's where the term came from.

 

[CCCMikey]

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