Rod Knock???


  • Rod Knock???

    Description:

    Sounds like a cat purring with a mallet.

    Much stronger than lifter noise

    Sounds internal and rhythmic

    Does not occur when engine is cold, only when hot.

    It happens in neutral and in gear

    Occurs mostly between 2k and 3k rpms

    Does not occur at wot

    Does not occur when decelerating.

    Only happens when accelerating or decelerating casually (light throttle)

    At first I was leaning towards worn rocker arm components but it was bad this morning when I got to work.

    I'm taking the valve covers off when I get home. I hope I don't have to drop the pan.

    Thanks.

  • #2
    Get a cheap stethoscope, or even the harbor freight variety and probe around the rocker covers
    and oil pan and see if you can better pinpoint where the noise is coming from.

    Removing the drivers side valve cover involves removing the upper plenum.
    Dropping the pan involves either removing the motor or the cross member.
    Both are things i would not casually like to do without atleast knowing where the noise
    is coming from. If the rod bearings/crank bearings are shot, chances are fair that the
    lifters are worn as well.


    84 AE/Shiro #683/Shiro #820/84 Turbo

  • #3
    Will do and get 2nd opinions from my buddies.

    I do however remember replacing the oil pump by undoing the motor mounts and lifting the engine many years ago???

    I'm a science teacher so there has to be a stethoscope around here somewhere???

    I just found 30 stethoscopes. lol

  • #4
    Rattle is coming from passenger side rocker.

    Sounds like lifters but.......

    I cut my oil filter open and there are metal shavings glitter like in consistency.

    I hope my rocker arm is destroyed and its not a bearing but at this point its like looking at a positive pregnancy test and saying its wrong.

  • #5
    Sounds like it may not be positive yet, but she's definitely hiding the pills.

    You could try to find some better/low mileage rocker assemblies off of a pick-n-pull
    Nissan Quest VG30/33 and see if that helps temporarily.
    But i'm guessing glitter also means bearing wear in the bottom end.


    84 AE/Shiro #683/Shiro #820/84 Turbo

  • #6
    Fingers crossed

  • #7
    Its official. I have to pull the motor.

  • #8
    Is it a boy or girl?
    '86 NA - original owner (1986-93) and final owner (2005-present)

    My build thread: http://z31performance.com/showthread…-Got-mine-back


  • #9
    Twins. The shavings are not magnetic so hopefully I didn't screw up the crank or rods.

    Motor is ready to be pulled. Might wait till the weekend so we can work during daylight.

  • #10
    Maybe it's worth doing a leakdown test before you pull it to see if you should go ahead and do the rings and cylinder hone
    since you'll have it torn apart for bearings. Ask me how i know


    84 AE/Shiro #683/Shiro #820/84 Turbo

  • #11
    Yeah. I don't know exactly what I will find but right now at the very least I'm looking at:

    1. New bearings
    2. New piston rings
    3. Hone cylinders
    4. New water pump, timing belt and oil pump
    5. ARP exhaust manifold studs
    6. Turbo rebuild

    If the crank and rods are good I might even rebuild the T5

    Engine is built with Wiseco forged piston .030 over, shot peened rods and Turbonetics 60-1.

    It has been balance and blue printed.

    She's coming out and really deserves the best.

    I was even considering rods but don't plan on making more than 500hp???

    Might have the heads checked out but they have been resurfaced at least 5X. Not sure I want to continue resurfacing.

    This will also be the 3rd time I resuse the HKS mls gaskets. I hope they are good.

  • #12
    Took the engine apart on Friday.

    The turbo bearings were gone as in missing. The turbo had about 3/8 play front to back and the turbine wheel was starting to tear up the housing.

    The crank and rod bearings were scratched up but it looks like I can get away with just polishing the crank.

    Lots of shaving in the oil pick up tube that were too big not to be sucked up.

    The hypothesis is that the torn up turbo bearings fell into the oil and those shavings the tore up the crankshaft bearings.

    Everything else looks good.

    So I'm rebuilding the engine, tranny, clutch and turbo for now.

  • #13
    damn dude hope you were ready to spend that dough, it is a bitch when you have one of those uh ohs, lol.

  • #14
    I was going to also get the rust cut out and paint the body.

    Guess that will have to wait.

  • #15
    Went to the machine shop.

    I need a new block and possibly crank.