Wining noise a few minutes after startup

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by msvx95, Nov 3, 2010.

  1. msvx95

    msvx95 Rockstar

    Recently my truck has started to make a whining noise after startup...engine running at idle and what sounds to be a bearing going bad. After I apply the accelerator the whining increases (similar to the sound of a blower on a custom car)....the noise sometimes lasts a few seconds or minutes after I press the accelerator at different pressures and it will be fine and noise goes away for the rest of the day.

    Has anyone experienced this problem?

    My thoughts are the alternator is starting to go bad (no dash lights yet) or an idler pully is due to be replaced..

    Anyone with good solutions?
  2. stephan

    stephan Rockstar 4 Years 5000 Posts

    I have a serpentine belt that makes this noise when the engine is cold. It usually goes away after 5 minutes or so. My idler pully also used to squeek, but I took it off & forced some grease into the bearings & it hasn't resurfaced in 2 years.
    I don't think yours is an alternator bearing, or any kind of bearing, as the noise would not go away. Once a bearing is dry & starts making noise it very seldom ever stops untill you grease it, or replace it.
    You might try popping the hood & attempt to locate the noise next time it's cold. If it's the belt, try putting a little bar soap on the belt. If it's the belt making the noise, the soap will temporairly quiet it down. Be very carefull when it's running where you put your hands & fingers ESPECIALLY in the area of the fan(s) belt, pulleys. I would soap the belt with the engine OFF.
  3. msvx95

    msvx95 Rockstar

    how can you really diagnose a noisy belt? I'm hesitant to put the bar soap on there...not sure how to really do that yet. I'd rather not do that while the engine is running.
  4. wis bang

    wis bang Rockstar 100 Posts

    The Clutch Fan in my S-10 did this...When I inherited dad's Jimmy it was quiet then that summer it would get hotter & hotter on the way home in the hot afternoon but never overheated and was fine in the cooler morning and at night.

    After replacing the fan clutch it roared every morning for a few min just like the pickup did...When you first start up the fan is locked up solid until the silicone warms up to slip some...

    It really does sound like a blower for a few min.

    I like my '05's electric fans...
  5. stephan

    stephan Rockstar 4 Years 5000 Posts

    Well you can either use soap on the belt, or just buy a new belt & hope you're not wasting your money. You can't diagnose a noisy belt by taking it off because you have eliminated everything else that could possibly be making the noise: alt, w.p., p.s., a.c., idler pulley, if you take the belt off, nothing is going to be

    I don't blame you for not wanting to do it with the engine running. That's why I said: "I would soap the belt with the engine OFF".
  6. msvx95

    msvx95 Rockstar

    Well it sounds as if the fan clutch could be the culprit. I've read a few threads about it. I will have to really diagnose it when I have some free time.
  7. Bigg G

    Bigg G Member

    This noise issue sounds exactly like the issue my truck is having. Has anyone else had this problem noise and what was your fix if you did ??????
  8. shibby2oo8

    shibby2oo8 Member 2 Years 100 Posts

    money on a/c belt tensioner. When I was in the shop that tensioner pulley is usually the first to go, then the other tensioner, water pump then alt. Take the both belts off and spin the pulleys and find which one is not spinning smooth, !0 min tops depending on is you have a serp tool or not. The a/c tensioner is down on the bottom of the engine and catches alot of crap
  9. msvx95

    msvx95 Rockstar

    it was in fact the a/c belt pulley on mine and no it wasn't 10 min to replace because without the correct set of tools I struggled trying to get my standard tools and my arms to get in there. I haven't heard any squealing in over 1 year so I'm happy about that.
  10. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    I replaced my AC tensioner with standard tools about three months ago. It took about 10 minutes. Luckily, I bought the gates brand with the one year warranty. It is making noise again. Guess that I will be pulling it off and replacing it soon.

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