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  • Cold Knock

    hey guys

    It has been a little chillier around here lately (into the 30's at night). Yeah I know, not that cold. But apparently it is cold enought to make the z do funny stuff.

    So after a cold night the Z gets grumpy upon start up. It makes a Knock-Knock-Knock From the area across from cylinder number one.

    I was kind of freakin out, but is only on cold mornings so I am skeptical.

    Here is what I have come up with on what it could be.

    A lifter up there isn't functioning correctly/sticking lifter. So maybe it isn't pushing the exhaust valve open far enough. Raising the compression, and making it knock. It only makes the Rod knock noise upon first startup and until I shut the engine off and start it again maybe 20 min later. Is it just a lifter not getting oil?

    I am pretty sure I am about 700 miles overdue for a oil change, so I will change it and see what happens.

    Let me know your opinions, thanks guys.

    Terrible idea putting those wheels on...

  • #2
    go to a lower number oil during the cold months

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    • #3
      lifter knock. mine does that until the motor get oil to the lifters. only in winter time.

      i run 10w 30 synthetic in mine. i need to rebuild the lifters.

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      • #4
        84z31 wrote: lifter knock. mine does that until the motor get oil to the lifters. only in winter time.

        i run 10w 30 synthetic in mine. i need to rebuild the lifters.
        yup. mine does that on those mornings when even the garage is cold enough to make a penguin's balls shrivel. An obnoxious taptaptaptap then a sudden odd silence when it gets oil. Gotta love how that car fires right off first try even when i forget to put it in the garage at night (which reminds me... :?).
        My beloved Z:1987 2+2 NA2T w/30a swap.
        My black sheep: 88ss parts car (pretty much stripped and gone)
        207k miles and counting. Turbo'd since 155k.

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        • #5
          mine always starts. even 30 below zero. nissan built a hell of a motor.

          i drive mine all the time. :lol:

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          • #6
            yeah, I was listening to it yesterday morning and it is coming from the left side/ front of the engine. So i take off the oil cap and get out my little flexible LED light thing and shine it in there.

            The intake rocker is moving the full distance and the exhaust rocker is barely moving.

            So I turn off the car, let it sit for a couple minutes. Start it up and look in there. The rocker it moving twice the distance now and the rod sounding knock went away.

            So i am gonna throw in another lifter and see what happens.
            Attached Files

            Terrible idea putting those wheels on...

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            • #7
              How loud is /was the knocking?

              I think I'm having the same problem. Loud noises from the same side of the engine, I changed the lifters, but it made no difference.


              EDIT: Mine was the exhaust manifold leaking. I tried to undo the nuts and a couple of the studs were snapped, they fell out when i got a spanner on them.
              Attached Files

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              • #8
                It is a constant knock that goes w/rpm.

                I have Dans TSS SS exhaust bolts. they are still there.

                It hasn't come back for like 5 days.

                Terrible idea putting those wheels on...

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