Engine Whirring noise & knocking?

Hi all,

On the way home I noticed that my engine started to make what I can only describe as a whirring noise at low rpm (<2000rpm) - never heard it before, normally it sounds more like "chug chug chug chug chug".

Also, I noticed that when I adjust the throttle, at what I would guess is between 1500 and 2000 rpm, I heard a faint knocking noise? Not sure if the two are linked, or if there is even a problem?

Here's a short clip of the engine running and me fiddling with the throttle:

The car is running perfect - I was driving when I heard the slight change in whine coming from the engine - I've been out since and it drives as normal, idle is perfect (around 800-900rpm as usual). As a precaution I topped up the oil as it was slightly below 3/4, probably because I recently did a 350 mile trip back home from Wales it dropped a bit.

So, I guess my main question is...is this something I should be worried about? Does the engine sound 'normal'? Any guidance/help/reassurance much appreciated!

Thanks all in advance -

Stuart

No that is not normal even for a single cam. Check the ancillary belts and pulleys that all are smooth free and that the crank drive is secure and doesn't oscillate. Also check the viscous fan hasn't found something to rub on. These are the cheapest and easiest to look at first. If they are all good it will become more complicated and expensive to resolve but do the easy stuff first.

Thanks Lambert.

Checked over all the belts, turns out it was a dry bearing on one of the pulleys. It's gone away now with a little directional squirt of WD40.

I think the knocking noise was me just being hyper-sensitive to any noises I could hear at that time; that was just the tappets in the rocker cover!