04 SR5. 4.0 L with 330K. I've been chasing a noise under the hood. Definitely a serpentine related pulley....it changes with the RPM's and gets louder. I really thought it was the alternator after using a stethoscope - it sounded pretty loud, and has probably been given me 200K miles. Replaced that.....along with one of the idler pulleys that seemed a little suspect. Noise is still there. I was leaning towards power steering (it has that huuummm of a power steering pump starting to go bad). I thought I would pull the fluid down and add some Lucas stop leak to see if the noise changed at all. No luck - sounds the exact same. Before I just start ordering parts......does anyone else have a suggestion or know if there is one particular part / pulley that goes bad first? I really can't pinpoint it unfortunately. It's the original a/c compressor and original PS pump.....so I'm leaning towards one of those. But I'm thinking it could also be a water pump, main crankshaft, etc. I could prob post a video if that would help. Any ideas?? Thx
