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strange periodic light knock under dash

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    #1

    strange periodic light knock under dash

    Hello again,
    I noticed a few weeks ago a strange knock under the dash. The knock soon went away and I noticed it again today, a few weeks later. It sounds like something is banging up inside the heater plenum. There is no rhythm to it. It is a light knock that sounds like something is banging on plastic. I thought it could be an O2 sensor possibly knocking against the transmission though it don't sound metallic in any way. I shifted thru the gears (PRNDD2) with my foot on the brake and raised the RPMS. There was no change in the loudness or rhythm of the sound. I have noticed it only at very low speeds or when stopped.
    The trans is a 1991 AOD.

    I am curious as to what a loose or bad torque convertor sounds like?
    Any others ideas as to the mystery sound?

    Thank you,
    Mike
    90 Colony Park LS with GT 40 heads and intake. HO cam, 65 MM TB, 67 MM EGR spacer. Has a 75 MM Pro Flow mass air sensor. Borla XS mufflers. 3L55. Shift kit, 2000 stall Tq convertor...Bilstein shocks, front and rear sway bars.
    90 Colony Park LS 64,000 miles all original. 3L55 tow package....front and rear sway bars.
    91 Grand Marquis GS....HO motor..Bilstein shocks poly bushings and police swaybars. This one handles the best.
    70 Torino Squire with M code 351 Cleveland 3.00 has Magnaflow mufflers. Hidden headlights and power windows. All original
    Tags: None
    #2
    Is it a buzzing noise? If so, thats one of the various AOD noises and totally normal. Apparently there is a specific check ball in there that gets a little loose in it's bore, and it rattles a bit.
    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC grandpa spec white and cranberry

    1984 Lincoln Continental TurboDiesel - rolls coal

    Originally posted by phayzer5
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

    Comment

      #3
      Originally posted by gadget73 View Post
      Is it a buzzing noise? If so, thats one of the various AOD noises and totally normal. Apparently there is a specific check ball in there that gets a little loose in it's bore, and it rattles a bit.
      No Gadget it seems to be more like tapping on plastic or a very light sounding back fire. Seems to be where the hamster wheel for the heater is at. It is not a consistent thing.
      Thank you and I wont worry unless something drastic happens.
      90 Colony Park LS with GT 40 heads and intake. HO cam, 65 MM TB, 67 MM EGR spacer. Has a 75 MM Pro Flow mass air sensor. Borla XS mufflers. 3L55. Shift kit, 2000 stall Tq convertor...Bilstein shocks, front and rear sway bars.
      90 Colony Park LS 64,000 miles all original. 3L55 tow package....front and rear sway bars.
      91 Grand Marquis GS....HO motor..Bilstein shocks poly bushings and police swaybars. This one handles the best.
      70 Torino Squire with M code 351 Cleveland 3.00 has Magnaflow mufflers. Hidden headlights and power windows. All original

      Comment

        #4
        could be a stick in the heater fan. Also, if the air doors are moving, sometimes they can creak and tick a bit. I would expect that to be more of an occasional noise than something kind of steady.
        86 Lincoln Town Car (Galactica).
        5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

        91 Lincoln Mark VII LSC grandpa spec white and cranberry

        1984 Lincoln Continental TurboDiesel - rolls coal

        Originally posted by phayzer5
        I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

        Comment

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