I have a 1989 Chevy z71 pickup truck. The engine makes a squealing noise and I noticed the battery gage drops down as well. Replaced the idler pulley already. Battery is new also. The squealing happens when its cold whether accelerating or sitting idle like when you first start it up. Help!!!

  • 1
    Was the belt replaced when the pulley was replaced? Is there a tensioner pulley as well? Certainly sounds like the belt is slipping.
    – JPhi1618
    Feb 16, 2016 at 17:04
  • The belt was not replace and yes it has a tensioner pulley. I forgot to mention the noise only happens when it's cold like in the winter. Summer time it doesn't make the noise.
    – user15105
    Feb 16, 2016 at 17:10
  • Add some belt dressing to the old belt. May have dried up a bit.
    – Dee
    Feb 16, 2016 at 17:25

1 Answer 1


Like others have said, it's your belt which is squealing. There are two possible reasons for this:

  • Your belt is worn out and needs to be replaced. The only way you can tell for sure on a serpentine belt is to use a measuring device. I've only ever seen one once. It measures the depth of the grove for wear.
  • The tensioner pulley is worn out ... well, to put it exactly, the spring inside the tensioner pulley housing is worn out. This would require the entire assembly replaced. You could possibly replace just the housing, but most will come with the pulley already attached. There should be a gauge between the swing arm and the mounting location to show you where it should be at if working correctly and providing the right amount of tension. It should be right on top, IIRC. You may also see the tensioner flexing a lot when under load (like when you rev the engine).

While putting belt dressing on the belt will help, it is only a stop gap measure. The dressing will wear off after a while and you'll be back to square one.

  • Could be the alternator bearings are on their way out. Sound like this? youtube.com/watch?v=yrh4Yi6YOSk
    – Tobin S
    Feb 18, 2016 at 17:51
  • @TobinS - I would highly doubt it, considering it doesn't happen during warm weather. If it was the alt bearing, you'd get it more pronounced during warm weather. Feb 18, 2016 at 18:27

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