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What does this sound like 2 U?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KapeKodK5, Jun 4, 2000.

  1. KapeKodK5

    KapeKodK5 Registered Member

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    I have a 1990 k-5 with A/C. Ever since I have owned the blazer, there has been a whine coming from the front of the motor. Everything has always run fine but, this whine drives me crazy. At idle it is not noticeable but increases gradually as the rpm's do. This leads me to believe it is a belt driven accessory... I am going to change the worn belt tommorow along with one of the idlers(the plastic one under the A/C unit) it is worn out of round. The best way to describe the whine is the sound your car radio sounds w/ eletrical interference coming through the speakers.If the belt and idler don't cure I am thinking something needs oil maybe. The a/c unit.... This whine has got me stumped and is driving me too drink any input on what this might be is greatly appreciated. My next step is the dreaded dealer...:(
     
  2. Depdog

    Depdog 1/2 ton status Author

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    The a/c compressor wont whine unless your air is on the the clutch is enguaged, or the clutch is bad, my personal opinion is that you alternator bearings are going bad

    Depdog

    <font color=blue>"Lead, Follow, or BECOME the Trail"</font color=blue>
     
  3. DMK

    DMK 1/2 ton status

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    If you have an air pump this could be making the noise.
     
  4. lew

    lew Registered Member

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    I would agree with the alternator bearing theory. My Iroc mad a similar sound prior to the alternator freezing up. Let me tell you on a serpentine belt system when the alternator freezes it will lock up the whole engine then trany, then rear axels, then tire.
    My iroc had a very near close encounter with a guard rail at about 90. I figured the motor seized but it was just the alt, You would figure the belt would break first but it didn't.


    Have fun.
     
  5. Bondo

    Bondo 1/2 ton status

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    I have a 90 as well. It had a similar noise in it that turned out to be the idler wheel that sits above the water pump. The one that acts as the tensioner. I replaced it and no more noise.

    BONDO WILL FIX ANYTHING!!!
     
  6. CK5

    CK5 In my underwear Administrator Premium Member GMOTM Winner Author

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    I also have a 90 and it was the idler pulley as well.

    Steve
     
  7. Blazer1970

    Blazer1970 1/2 ton status

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    A lot of times, you can isolate a noisy accessory by removing the belts, and turning stuff by hand. If it has its own belt (A/C?), just take that belt off and drive. I would not rule out the A/C compressor, since part of the clutch turns all the time, and that could be the culprit. If the bearings are going bad in the alternator, you should be able to feel it when turning it by hand. Ditto with the air pump.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  8. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    I had a funny noise under the hood and I took a long screwdriver and put the tip on the altermator, waterpump, air pump, A/C, and stuck the other end in my ear. It makes the noise vibrations go right to your ear and you can isolate the trouble that way or get one of those fancy stethescopes. It was my alternator, you could really hear it. I think in Hayes or chiltons it even tells you what to listen for.
     
  9. GMC4by4

    GMC4by4 Registered Member

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    Those idler pulleys do tend to make that noise. Try taking a long pipe, like the handle of a hydraulic jack, and with the engine running, carefully place one end to your ear and the other end to different parts of the engine. Try listening to the alternator, idler pulley, A/C compressor, etc and you should be able to isolate where the sound is coming from. Kind of like a big K5 stethoscope. %^)

    -Rick
     
  10. dumbfounded

    dumbfounded 1/2 ton status

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    Just try taking off the entire belt. I'm assuming it's serpentine. If you don't run it long it won't hurt anything. Just remember that the water pump won't be spinning so don't let it heat up. I'd probably bet it was the idler pulley, change it anyways it's cheap and can't hurt. My camaro's idler wore out broke off and added $100 b/c the belt was screwed and it took out 2 sensors off the engine when the belt wrapped around them. Also the car had to be towed (AAA no cost) plus it sat for a week and a half waiting for parts. So go on and change it.

    Wasn't me.............
     
  11. jarheadk5

    jarheadk5 1/2 ton status

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    I'm a little late here, but have you checked your power steering fluid lately? EVERY vehicle I've owned or worked on (with p/s) needed p/s fluid when that type of noise started. The sound is the p/s pump cavitating, which is murder on the pump's internals.

    [​IMG] Semper Maintenance!
     

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