Whistling noise on cold start. Help need it

So this morning when I started my truck in the early morning it was making a whistling/chirping noise while idle. When I hit the gas the whistle noise got louder under acceleration. After it warm up it when away again. I drop her off with my mechanic who would check it out in the morning. Any ideas what you'll think. Thanks in advance guys.

 

Mine does this as well during this time of he year. It runs fine so I'll be looking to see what the problem is. Mine usually shuts up after a 15-30 seconds though.

 

Mine dose the same thing, I started it in freezing degree weather the other day and it was doing it bad, mines more like a high pitch whistle that gose away after the truck reaches about 120 degrees I have a feeling it's either my fan clutch bearings getting old?! Verry unlikely, but I need to change anyways so it could be a possibility but I think that one of my pulleys got oil on it or somthing cause belts all look great and they feel solid maybe alternator going bad?! I know my battery's on its last leg so maybe it's the alternator trying to catch up but it's just very cold? I've thought long and hard on what it is but I don't think anything is wrong with it just yet, if I ever hear the noise when it's warm then I'll tackle the belts ASAP, would love to hear what was your problem but we have diffrent motors and I don't think we have the same noise

 

Yes exactly high pitch whistle noise that's what mine sounds like

 

Yeah in my mind I think everything is just very cold when I start my truck in the morning and everything turning is just trying to warm up and get a bit softer.... If that makes any sense

 

My mechanic said its not normal, plus my last tacoma didn't make any noise no matter how cold it was

 

i can't seam to find anything wrong, But not all trucks are the same some things wear diffrently than others , I don't see a reason to tackle anything just yet

 

I hear you, that's what my mechanic told me and he's a pretty ones guy. So I'll let you now what happen

 

I grew up building jags, bentlys and rolls Royce's with my uncles, so I'm probably thinking REALLY REALLY HARD

my uncles laugh at me a lot and tell me I'm putting an engineers brain to a simply truck, they tell me my belt is just a little lose and to not stress over it

They laugh when I tell them about alternator being cold or oil on the pulley, they respond almost always with "it's a friggin Tacoma triztan not a xj12 your overthinking it" I bet we just have a slightly loose belt

 

Sounds like the belt tensioner pulley bearing. Common problem with these trucks, the AC belt tensioner sits very low and catches water and gunk. Very cheap/easy fix. You can replace the bearing with another 6301 bearing

https://www.tacomaworld.com/threads/ac-adj-pulley-bearing-gone-bad.268563/#post-6709260

 

Update!!! Apparently the problem it's the fan clutch assembly. That's what my mechanic told me.

 

My mechanic told me that it's is the fan clutch assembly.

 

This part right here