Mysterious sound from engine

Sounds like: Knocking noise.

Happens when:

• within the first 3 minutes after putting truck into any gear
• gets slightly louder when I turn the wheel
• the blower fan is on, heat or air
• gets very loud when a/c is on
• goes away with acceleration
• only hear it when engine first starts

Truck: 2008 Prerunner V6 with towing pckge. 134K miles.

I brought it to dealership - they heard the noise but couldn't figure out what it is. Honestly, I can't stand dealing with them and have always had more luck fixing s*** myself. (when it is the simple things)

Any ideas on what it could be? I'm trying to sell the truck and want to fix these things before I sell it.

Thanks in advance.

 

Sounds like it could be the a\c clutch or maybe the tensioner. Does it do it with the a\c off?

 

Yes. But it goes away completely when I accelerate.