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  1. #1

    Default Rattle question.

    I have a fairly loud rattle under the hood that only happens
    when It's cold. I say rattle because the tempo doesn't change
    when I raise the rpm. After it warms up it stops. Anyone ever had
    this problem or have any ideas.

    All I can tell for sure is It's under the hood. Thanks for any
    replies.
    91 Suburban 5.7 1500 4wd

  2. #2

    Default

    Could be a lot of things, but stopping after it warms might point to an exhaust pipe hitting something.

    Could also be due to the engine shaking when cold and getting sooth when warm (if it does do this).

    Might be the hood hitting a stop.

    But, I know if it was me, I'd have the hood up and be trying to pin point the area.
    Ray

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  3. #3

    Default

    Thanks Ray.
    I have raised the hood but can't seem to pinpoint the noise. Sounds like from the passenger side. I'll try to get another set of ears. I was taking a shot in the dark that someone's had the same problem. I will take a better listen to the exhaust pipes. Thanks for the response.

  4. #4

    Default

    When you say it quits when warmed up,,,,, as in short warm up time like exhaust getting hot or slow warm up time like the radiator/cooling system.
    2010 Silverado LT 1500 5.3L 4X4
    '95 BMW K1100LT
    '97 BMW K1100LT

  5. #5

    Default

    Short warm up. Although the colder it is, the longer it takes. Hard to explain.
    It sounds almost like a rod knocking as far as volume. But I know It's not that.
    I need a mechanic here when I start it. Oh well. I'll keep trying.

    Thanks for your response.

  6. #6

    Default

    Quote Originally Posted by jbopeep View Post
    Short warm up. Although the colder it is, the longer it takes. Hard to explain.
    It sounds almost like a rod knocking as far as volume. But I know It's not that.
    I need a mechanic here when I start it. Oh well. I'll keep trying.

    Thanks for your response.
    I just traded off my old 2000 K2500 WT that had a low end(rod) knock when cold, and even really pronounced when below 0F.
    It had been getting progressively worse over time.

    What are you using for oil, Dino or Synthetic.

  7. #7

    Default

    It only does it when It's cold. Like around freezing. Wouldn't it
    do it after sitting for a couple days until the oil circulated?
    When it's warm, doesn't make a sound.

    BTW..... I use regular oil and it's been changed every 3-4 thousand
    for years.

  8. #8

    Default

    That's sounds strange. I would have thought that if it were crank/rod/cam related to oil issue, the noise would change sound/level with rpm changes.
    Yet you say it doesn't make any difference at what rpm, the noise is the same, other than it's present when outside temps are cold and not present when warm........

    If it were an older mid/late 70's I'd say look at the exhaust butterfly valve, or the heat riser tin housing on the manifold.......

  9. #9

    Default

    Actually it gets quieter when I give it a little gas. Definitely doesn't become faster with more rpm. That's why I don't think it's a rod or something internal. It kinda sounds like it's coming from the passenger side exhaust manifold.

  10. #10

    Default

    Could it be a solenoid or something that going crazy until the engine is warm?
    1997 Chevy K2500HD 6.5 TD Vin: F ... 1995 Chevy Suburban C2500 5.7

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