TAP TAP TAP Where that sound at?

Discussion in 'Modifications And Maintenance' started by morganm, Apr 27, 2009.

  1. morganm
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    morganm New Member

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    97 Impreza OBS (engine is a 95 Legacy) - 178,000 miles

    I had a tick that turned to a tap that is now constant and loud. Rarely it will go away but always comes back. It's been like this for several days now. At first I thought it was typical Subaru lifter chatter so I Sea Foamed it and just did an oil change. I really don't think it's a lifter and here's why.

    Took out my trusty needle stethiscope to pinpoint the noise and could not find any source! You can use this to find out exactly which lifter is making the noise; it's a fairly precise tool. The entire valve train is quiet (even for a Subaru!). The block is quiet, tranny is quiet, and everywhere else I put the needle it was quiet. Loudest things I found were the fuel injectors but the sound didn't match.

    When I first start it up it's really loud then it quiets a bit after 1 second but still annoying. At 2500 + RPMs it's much quieter but still present. Every now and then it will go away.

    Spent about 8 hours on it this weekend. Took off fans, belts, and wrestled with the rust-welded timing belt cover bolts. Finally got the left and right timing belt covers off (not the center one; wasn't in the mood to take the main crank pully off by then) Belts felt tight and I could not move the tensioners with my fingers. Started it up; belts still looked tight (no flopping) and I could watch the tensioner pullies; no bouncing.

    While it was up on jack stands and running with the tapping noise I went over everything with the stethiscope again... NOTHING. Everything is quiet and what little noise I do hear is way more quiet and different than the tapping noise.

    Thought maybe the flex plate on the torque converter was loose. So I rolled it over by hand and poked at the flex plate; seemed tight. None of the bolts holding it on were very loose. Put it all back together and drove it to work today.

    It comes and goes; sometimes it stops making the noise and then it starts again a few minutes later. The rate at which it taps (Taps Per Minute? =P) increases with RPMs and gets more quiet with more RPMs ... I'm at a loss
     
  2. AWDimprezaL
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    AWDimprezaL has more posts than you

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    HLAs, mine does it too, the noise comes and goes, they just wear out eventually. Try thicker oil.
     
  3. morganm
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    morganm New Member

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    But you can hear bad HLAs with a stethiscope quite eaisly. So well that you can actually pin point which ones are bad. As I said above; the valve train is completely quiet (even for a Subaru!)
     
  4. Chux
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    Chux Well-Known Member

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    Morgan used to have an EA82.......he knows what noisy HLAs sound like ;)



    did you poke your stethoscope at any of the accessories? we had a funny sound early one summer on my mom's '92 Legacy a few years ago. We were real worried that it was something severe, but it turned out to be the A/C compressor.....


    maybe something in the trans? does it change when you put it in gear?
     
  5. morganm
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    morganm New Member

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    Yep; checked all accessories.

    It does change when I shift from say Park to Drive or from Drive to Neutral but so does the whole engine as you are loading or unloading the engine from the tranny. So it's hard to say; is it because I'm loading/unloading the tranny or only because the engine is also changing RPMs when I load/unload the tranny?

    Best guesses right now:
    - Torque converter + backing plate (still not ruled out)
    - Something else in tranny? Pump?
    - Oil pump backing plate loose

    Open to more ideas! =)
     
  6. jrthechef
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    jrthechef New Member

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    i had a spark plug work its way loose on me once in me 93 legy
     
  7. Chux
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    Chux Well-Known Member

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    huh....sounds like you've checked everything I can think of.......
     
  8. snowman
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    snowman New Member

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    Tensioner tick?

     
  9. morganm
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    morganm New Member

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    Checked sparkplugs; tight all around.

    Checked tensioner pullies a few days ago

    Gonna check oil pump backing plate tonight.

    I'm still leaning towards tranny; more specifically the torque converter. However no conclusive evidence there.
     

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