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Something other than spark knock that rattles

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  • Something other than spark knock that rattles

    I have a rythmic rattle coming from the direction of the right side of the engine at 1500-1700 rpms under light to medium load. It's not very loud, my dad can't hear it, but I can and it drives me nuts.

    I've tried retarding the timing in the past, and tried premium gas, neither of which seemed to change it.

    The last couple days I tried premium again with the intention of retarding the timing at the same time, but tonight I realized it's already at 7-8*TDC, which hopefully explains my loss in mileage over the last month.

    So other than a loose rocker, or maybe rod or main bearing (the engine is new) what else could possibly cause a rattle.

    I tried attaching a stethescope to the plenum and routing the tube up through the hood and through the window, but I couldn't hear anything (couldn't hear it without the scope either, as the noise with the window cracked drowned it out)

  • #2
    Could be trans or exhaust related.
    Lifting my front wheels, one jack at a time.

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    • #3
      possibly the best tensioner messed up. My 1996 Grand Prix 3100 started doing that, and it was the tensioner going bad.

      Check that out.
      Taylor
      1988 Olds Cutlass Supreme 3100 MPFI
      1990 Pontiac Grand Prix STE 3.1 MPFI
      1994 Olds Cutlass Supreme convertible
      1998 Lincoln Mark VIII
      "find something simple and complicate it"

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      • #4
        Does it happen while parked? If so completely remove the belt to determine if it is an accessory or not.
        1993 EXT. CAB, 3.4L V6 TBI, 5spd manual. Sonoma
        1990 4Door, 3.2L V6 TBI, 5spd manual. 4X4. Trooper
        Because... I am, CANADIAN

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        • #5
          Tensioner pulley is new. It was squeeling before. It also had the rattle before and after the pulley swap. The rattle started suddenly not long after I put the engine in.

          I can't get it to do it while parked. Only under a certain load. Maybe 1/3 throttle I guess. It'll do it in any gear while mildly accelerating, and when I'm cruising at 1600ish rpm, I can let up on the gas or give it more gas, just a little either way, and it goes away. I think I can almost hear it again around 2000 rpms, but I'm not sure.

          I need a set of rollers or something to set the back wheels on so I can run the car in gear at the right rpm and listen for it with the hood open.

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          • #6
            Originally posted by jeff89fbird View Post
            I need a set of rollers or something to set the back wheels on so I can run the car in gear at the right rpm and listen for it with the hood open.
            Jackstands? I've run my car several times with either the drive wheels just in the air, or the entire car in the air. As long as you have it supported well, and you aren't looking at revving very high, jackstands shoud do just fine.
            -Brad-
            89 Mustang : Future 60V6 Power
            sigpic
            Follow the build -> http://www.3x00swap.com/index.php?page=mustang-blog

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            • #7
              Im guessing its gotta be one of the mounts, either engine or tranny.
              sigpic
              1994 Oldsmobile Cultass Supreme SL
              3400/Getrag 284 5spd
              1995 Chevy K1500 350c.i. 5spd Z71
              350/NV3500 5spd
              2014 Chevrolet Malibu LS

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