Harmonic Balancer Crank Pulley Gone Bad ? vibration at 3K

  • #1

    Harmonic Balancer Crank Pulley Gone Bad ? vibration at 3K

    I am wondering if the crank pulley can go bad … I get a vibration seemingly from the engine at about 3000-3200 rpm 1985 NA AT . that goes away above and below … Can I get vibration from the AT in park reving the engine ? This one car has had it since I bought it years ago … How do I get rid of it ?

    any thoughts ?
  • #2
    Crank pulleys can go bad, yes. Most have a layer of rubber in them that separates, though this typically results in the "rings" themselves coming off. Most Nissan engines are "internally balanced", so having a bad crank pulley shouldn't cause major carnage like it would on an "externally balanced" engine. Which also leads me to believe perhaps your crank pulley isn't your issue, as your engine won't be "out of balance" if your crank pulley separates.
    1985 300ZX Z31 2+2 VG33ET (running!)

    Comment

    • dbruce
      #2.1
      dbruce commented
      08-01-2018, 08:10 PM
      Yes that's what I've been thinking… the vibration is coming from somewhere …
      My real experience is with flywheel/clutch cars where I'd get the flywheel balanced " just to be sure " when I put an new clutch in .

      can a torque converter be out of balance ? If I rev the engine to 3k does the torque converter follow? I am not very smart about this …
      I just took it out on a run and brought it to 5500 over hill and dale and felt a mild but steady vibration all over 3K to the top of the range …
      If the car was new I'd take it in for warranty … oh that's right its 30 plus years old and 240K miles …
    • albionwanderer86
      #2.2
      albionwanderer86 commented
      08-01-2018, 08:35 PM
      Yes, torque converters can cause a pretty bad vibration. Typically manufacturers mark a particular spot on the torque converter with a dot, and a similar spot on the flexplate, and you line up the two to ensure no vibration. Perhaps the previous owner had transmission issues, and the shop incorrectly re-installed the torque converter. It is also possible it could be a driveline vibration in the driveshaft.
  • #3
    I've been doing some reading on this subject… and I haven't really come up with a definitive answer. Some suggest u-joints in the driveshaft, some same pinion angle and differential issues, others say engine / transmission mounts, and still even more even suggest misfires. The best option would be to take the car to a driveline shop and have it looked at. It might be worth whatever their inspection fee is to get either peace of mind, or find out exactly what is wrong and fix it.
    1985 300ZX Z31 2+2 VG33ET (running!)
  • #4
    Put the car in neutral or park, check to see if vibration is still there. If it still has vibration it will not be u-joints/driveshaft.
    • 1 like
  • #5
    Originally posted by Gem84Znt View Post
    Put the car in neutral or park, check to see if vibration is still there. If it still has vibration it will not be u-joints/driveshaft.
    albionwanderer86 commented
    Today, 02:35 AM


    Yes, torque converters can cause a pretty bad vibration. Typically manufacturers mark a particular spot on the torque converter with a dot, and a similar spot on the flexplate, and you line up the two to ensure no vibration. Perhaps the previous owner had transmission issues, and the shop incorrectly re-installed the torque converter. It is also possible it could be a driveline vibration in the driveshaft.
    Yes this AT was rebuilt 22 years ago (before I bought it) and the car seems to have always had the 3K rpm vibration (in park/neutral) … So when it was rebuilt they might have missed something … It's definitely in the engine/trans area .
    and I've read how the torque converter with age can deform and lose balance ( ie needs to be replaced) .
    Last edited by dbruce; 08-03-2018, 07:04 PM.
  • #6
    From what I've read , the TC Torque Converter may well become out of balance due to age It becomes deformed and friction particles accumulate inside … So it probably needs to be replaced …