Engine noise on startup, goes away as it warms
 

Noise follows rpm, but not consistently. disappears after only a few minutes of driving, or as temp warms Possibly accessory related.


Anyone know what this is before I start swapping parts?

Sounds kind of like a pulley bearing going bad, like the alternator bearing or the AC compressor bearing.

Could be the belt, a bearing like alternator or idler pulley...

You can spray some WD40 on the belt to see if it goes away...and also into the idler pulley and alternator one at a time...when it quiets down you have your problem. Belt is cheap...others more..so start there :)

I'm going to replace the A/C belt tensioner as it seems to be siezed and I can't adjust it, so that will allow me to rule it out. I don't believe its the A/C compressor as the sound doesn't change if the clutch engages.

Hoping its not the alternator for cost reasons. Will the car freak out if I run without the belt for a few seconds? My other worry is that it only does it when cold, so I don't want to be only running the engine for a few seconds before shut off and risk flooding it :/

Much more likely to be the belt or the tensioner

You can run it without the belt cold for a bit...but remember no water pump so it will overheat if you do it too long. You can run it plenty long enough to make sure it is that system.

When you have the belt off...turn the water pump and make sure it is smooth...if it catches or feels rough you might want to replace it at that mileage if you haven't done it already

Swapped out alternator. Problem solved.