Top end knock / rattle?

[Chris E]

Hey guys

Not really a problem as such just wondering what your opinions would be on this issue.

I've got a Vr v6 that was cammed/rebuilt etc by the previous owner. Its developed a slight knock/rattle which dad thinks may be a cam bearing or maybe the tappets need to be adjusted. You can hear the rattle on idle, it isn't very loud and you need to listen to hear it. Dad doesn't know commodore motors to well so he's not sure. Any ideas what the rattle might be?

High in the rev range when under load its also making a knocking sort of noise...hard to explain what I mean.

What I'm basically asking is if these noises are warning sounds its about to go very bad very quick?

[hako]

The tappets are hydraulic and self adjusting but they can tap if dirt gets into one. The rattle or the knock may also be the balance shaft bearings knocking especially if the engine has done over 250,000km.
Rattles/taps can also come from one or more of the pulleys that the serpentine drive belt runs.

[Sgt Santa Cruz]

9/10 that rattle will be the balancer shaft needle bearings if it wasnt taken out or had them replaced during the rebuild. it sits in the valley to counter excessive power pulses and vibrations