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Noisy engine during idle, e fans, underdrive pullys

Discussion in 'General Chevy & GM Tech Questions' started by b-radical, Jul 25, 2012.

  1. b-radical

    b-radical New Member

    The engine in my silverado is somewhat noisy. It sounds like something loose or rattling during idle. I've had bad experiences trying to fix things that aren't broken, but I'm willing to try to quiet my engine down some if its not too much work. I know th knocking/ pinging is not worth the trouble. I had the ac tensioner replaced about 30k miles ago. I've also had some front end damage so I wouldn't be suprised if something was bent and causing the actensioner to wear out prematurely.

    What can I look for and/or replace to get my engine to run quieter? Are there any parts that are prone to making noise?

    I've seen some trucks wth e fans and underdrive pully's. What are the underdrive pully's for? would e fans help?

    Thanks for all the help
  2. rileyjr16

    rileyjr16 Active Member 1000 Posts

    It could be the tensioner for the serpentine belt making noise.

    An Underdrive pulley refers to an aftermarket crankshaft or accessory pulley (such as an alternator pulley) that is designed to drive a vehicle's accessories at a slower rate than stock. Underdrive in general means the input rate of rotation in a system is greater than the output rate of rotation. However, an underdrive pulley is considered to be an accessory pulley that is larger than the stock pulley, or a crankshaft pulley that is smaller than the stock crankshaft pulley, even though the accessory may not necessarily be underdriven with respect to the crankshaft pulley.

    Underdrive pulleys usually are marketed as a performance enhancing item that increases the torque and horsepower output of an engine by reducing parasitic drag caused by belt-driven accessories, but more importantly by reducing the moment of inertia. Horsepower gains from underdrive pulleys alone are possible. Independent dyno tests have shown up to 15hp increase at the wheels after installing an underdrive pulley.
  3. b-radical

    b-radical New Member

    Very comprehensive answer. Thanks Charles
  4. ChevyBoy2009

    ChevyBoy2009 New Member

    Run some sea-foam thru it and that should stop the pinging/knocking for awhile...your motor will like that :great:
  5. b-radical

    b-radical New Member

    Turns out it was the idler pully making all the noise. will look in to seafoam, thanks.

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