Help me diagnose weird engine noise

I’ve been trying to diagnose an engine noise I’m having during idle. 2013 V6 4x4. Not the Tacoma tick, I’m well familiar with that one.

It sounds like grinding but happens on and off randomly. Occurs sitting still and slow speeds, and at highway speeds gets drowned out by wind noise. Very intermittent and random noise. Not affected by steering or using heat / ac. I’m thinking it could be a pulley going bad or bad belt? Doesn’t squeak or chirp, but it honestly sounds similar to an old computer loading or an old school printer.



I have sprayed wd40 on the belt to see if the noise changes but no dice. Also burped the air from the radiator after a coolant drain and fill, no air present. Tried higher octane fuel, no change. Any ideas what this could be?

Thanks in advance for any help.

 

I'd remove the belt just to rule out something in the accessory drive, just cant run it long like that since your water pump won't be turning.

 

Yup, on a cold motor, pull the serp belt off and start it up.

 

Good advice. Will try and do that after the holidays. Anyone had experience with a similar noise with their trucks?

 

I'd suspect something in the Serp belt route. Likely bearing related.

Pulleys, tensionor....... or one of the driven accessories has a bearing on it's last legs.