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a tap sound

Discussion in 'XJ Technical Chat' started by Fongdingo, Feb 2, 2007.

  1. Fongdingo

    Fongdingo Member

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    Do the valve shims make a sound if they are not right? I havent done anything to them or even seen them. I did clean the carbs recently, and its running better, but now a tap or clicking sound occurs from the top of the bolck. It goes away after it gets warm. Any thoughts to this sound?
     
  2. Danilo

    Danilo Member

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    Valve adjustment, shim clearance is a bit too big. Usually at worst when cold. Strange though, as the clearances tighten over time.. somebody get in there and bungle a valve adjust/shim replacement recently?
     
  3. Fongdingo

    Fongdingo Member

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    no one has been in ther recently but i also dont know the last time someone has ither.
     
  4. MiCarl

    MiCarl Active Member

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    I just did my shims and they are to spec. When cold the engine sounds like everything in it must be loose, quiets down once it warms up.

    I'm hoping this is normal.

    Not too bad an idea to check the shims anyhow, not hard to do. Remember they need to be checked at room temperature. Not hot, or at the 10deg. we have here in Detroit but 68deg.

    If you find you need shims THESE fit and are way less expensive than the stealership.

    If you need a shim tool JC Whitney has one for way less than they go for on eBay. The picture on the JC Whitney site is incorrect, you will get the correct tool.
     
  5. bosozoku

    bosozoku Member

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    A little bit of valve-gear yakking is normal, especially for an air-cooled engine when it's cold. As long as there's no clattering after it warms up, you're probably OK.

    I'd worry more if it was too quiet, as that can be a symptom of valves without enough clearance. It may also be a pain to start, and will probably have poor idle quality when the valves are that tight.

    As has been suggested, take a peek under the valve cover to see what's really going on in the valve-lash department.
     
  6. samsr

    samsr Member

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    Check your vacum line to the petcock. It may be lose or cracked causing it to lose vacum. My 750 used to do the same thing. Sounded like a little lepricon was in the tank with a small hammer. I thought it was the valves at first but ended up being the petcock diaphram. Took a while to find. Sounded louder with a close to empty tank. Hope this helps
     
  7. RickCoMatic

    RickCoMatic Well-Known Member

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    Probe the engine and listen for that noise.

    Here's a new twist on making a real great engine probe.
    Cut a 4 or 5-foot section of fiberglass rod. The long fiberglass rods we New Englander's use to show the snow plow guy where the lawn begins are perfect for this.

    Glue a "Replacement pencil eraser" ... (the kind you bought to stick on the paper shredding cylinder when you used-up the OEM pencil eraser learning long division) ... to the "Listening-end" of the rod ... and you got yourself one of the best engine noise probes that money can buy!

    Put the bare end on the engine block where you want to probe for noise.
    Listen to the eraser end and determine if the noises are good or bad.

    Find-out where the noise is coming from.
     

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