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The unidentifiable intemittent oscillating noise!

Discussion in 'The Garage' started by BorregoK5, Aug 9, 2003.

  1. BorregoK5

    BorregoK5 1/2 ton status

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    I picked up a new noise after the last run, thought it was a broken hub but after taking it apart found nothing was wrong. The noise sounds like something that was spinning suddenly went out of balance and oscillated to a stop (thinking its a bearing race somewhere). It kind of resembles the sounds a radiator cap makes when you overheat and it blows off steem past the rubber seal. I can feel it in the floorboards and a little in the steering wheel. Its completely intermittent and definately coming from the front end somewhere. It happends at all different speeds and doesn't change with speed. It happends at all different RPM and doesn't change with RPM. Its the same with the front shaft engaged, disengaged or removed, hubs locked or unlocked. I disconnected the electric fan just to make sure it wasnt the cause and it wasn't. I'm running out of things to check and still no closer to finding it. Its beginning to get more frequent (used to only happen on the freeway, now its happening everywhere). Unfortunately theres no trigger to make it happen yet, still random but I'm beginning to fear whatever it is is going to go out soon... and I'm destined for a 200mi drive. Anyone have a strange one like this happen which sounds similar?
     
  2. Twiz

    Twiz 1/2 ton status

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    [ QUOTE ]
    intemittent oscillating

    [/ QUOTE ]

    Common symptom of a drive-line related vibration, such as a bent drive shaft or failing U-joint. Drive-line problems usualy have a "boom" like sound or feel. The frequency is often too low to actualy be a noise, they act more like a vibration. Remove and inspect drive-shafts and u-joints.

    The rest of the post pretty much shoots that idea right in the foot, tho'.

    So, Something grounding-out might cause an intermitant "low" rumble/vibration/noise (I assume it's "Low"). Something that should be isolated by some sort of rubber mount - isn't.
    Such as:
    - Exhaust system grounding out on the body or frame. Might be able to duplicate it in the stall by power-brakeing the engine and slowly increaseing the RPMs while looking for the "sweet-spot". As the engine torques over, the exhuast system will follow, makeing some clearance change dramaticaly.
    - Engine or Tranny grounding out on the frame or cross member. Tired or torn motor/tranny mounts. Engine is not mounted correctly (twizted or cocked one-way or the other). Should be able to duplicate it by power-brakeing and slowly increase engine RPM.
    - Hoses or tubeing grounding out. P.S. lines, brake lines, fuel lines, just about anything can transmit noise. I've even found a throttle cable transmit a rattle to the throttle pedal because it was laying on the PCV hose.

    If it's really wacked out, it might be a an internal problem with the trannsmission or engine.
     
  3. BorregoK5

    BorregoK5 1/2 ton status

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    Its a high pitched noise with a high vibration factor, definately some kind of oscillating part. It sounds like a bearing does on an electric motor when the bearing gets loose and the main shaft is allowed to vibrate in its race. In fact, it sounds a lot like one of those Ahh-Oooog-Ahh horns do durring the Ooo part. Many cars I've past when this happens think I've honked at them!
     
  4. K10ANDYKHAMNIC

    K10ANDYKHAMNIC 1/2 ton status

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    water pump ? alternator ? powersteering ? only when driving or stationary also ? /forums/images/graemlins/ears.gif i dont hear it . /forums/images/graemlins/thinking.gif
     
  5. arq

    arq 1/2 ton status

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    /forums/images/graemlins/crazy.gif nail inside your tire, torque converter, what andy said, worn brake pads...

    ARQ.
     
  6. Confedneck

    Confedneck 3/4 ton status

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    at all rpms, whistling kind of noise that oscillates..and you can feel it in the wheel...something foreign trapped in the top of one of the calipers making contact with the rotor? air down real low and something popped past the bead? just trying to trigger a lightbulb
     
  7. Twiz

    Twiz 1/2 ton status

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    [ QUOTE ]
    water pump ? alternator ? powersteering ?

    [/ QUOTE ]

    I'm kinda leaning towerds one of those too, now. Could start pulling belts off and drive it to see if it changes. You might even be able to feel at the pully. I've seen P.S. shafts sheered off, alternators explode, and water pumps break. So, it's possible.
     

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