A night or two ago I developed an odd *whirring* noise, kinda like a quiet vacuum leak that eminated from below the water pump. I was driving, no noise, then I hammered it, let off the throttle, and the noise was there...pretty loud too, I might add. It originally sounded like it was coming from the passenger side bank of cylinders, but, upon closer inspection this morning, found it is actually coming from below the water pump.

Hesitantly, I drove it to work and back today(like 1.5miles) and found that the noise has hushed exponentially with each start up. Other than the noise, the truck runs identical to before, no change in noise from the actual valvetrain or fuel injectors. Also, the water pump was new and only has ~10k miles on it, so I don't think that is it. Like I said, it seems to be coming from below the pump, around the right side of the A/C pully.

Should I be worried? Anybody else have something like this happen to them? THanks in advance!

 

It could be the ac idler pulley or compressor/clutch. I've had noises with both....so far I've replaced the upper and lower idler/adjuster pullies, and been living with intermittent noises from both my ac compressor and power steering pump. My ac compressor actually makes a scraping type noise when it isn't engaged sometimes, and other times it's quiet. When I start the truck ice cold, I hear all sorts of scary noises from under the hood until it warms up...from squeaking, ticking, tapping, piston slapping, to the sound of gremlins running away lol.

I wouldn't be too worried...if the noise persists and you can track it down, then you can fix which ever accessory is making the noise if that helps you to sleep at night.

 

Yeah, I ran it a bit with the hood open and dug my head into the engine bay, and it seems to be coming from one of the A/C idler pullies like you said. Is it that difficult to replace? I just need to take the skid protector off right?

 

It's a piece of cake...remove the belt and unbolt the pulley...can't remember if I removed the skid plate but I probably did. I think that 2 or 3 13mm bolts hold the tensioner in if I remember correctly.