Car vibration and I'm Dumbfounded!

Discussion in 'The Bench' started by 71Skylark1384, Jan 12, 2018.

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  1. 71Skylark1384

    71Skylark1384 Platinum Level Contributor

    About a week ago, the car started to vibrate really bad. It just came on all of a sudden without any warning. Was at a stop sign and I gave it a good push on the pedal. Then about a few feet down the road at cruising speed the car started to vibrate.
    Turned it off and then back on. Still vibration even in neutral. It seems like the higher the RPM's the more violently it vibrates. I changed the motor mounts and even checked the flywheel (which still has the weight on it). Spark plugs look all god except 2 of them are a little dark. I'm no mechanic but I have a Mechanic Stethoscope, which I used on each piston and exhaust, everything seem to sound good all the way around. I am dumbfounded what it can be. Anyone have any ideas? It will be greatly appreciated.

    Thanks
    David
     
  2. RIVI1379

    RIVI1379 Well-Known Member

    Look at the harmonic balancer... May have spun or just plain left.
     
    john.schaefer77 likes this.
  3. john.schaefer77

    john.schaefer77 Well-Known Member

    I agree. You're timing mark should be lining up with the keyway. Easy to check.
     
  4. yachtsmanbill

    yachtsmanbill Well-Known Member

    X2... Thats happened to me before on an SBC of all things; never was able to walk back and find it. Check for a missing fan blade as well. To dig any deeper could be a broken vane inside the torque converter, flex plate cracked/seperated around the bolt holes, even as far as a chunk of crankshaft counterweight broke off.
    How about a weird one? Are the dark plugs #'s 7 & 8? Camshaft broke off at the back two cylinders. Pull the easiest valve cover to inspect valve movement. On a simpler note, maybe just the distributor drive gear roll pin sheared and spun the gear a few teeth outa time. Itll run really lousy and shake like a paint can shaker at the hardware store, but still run. Oil pressure still good? ws
     
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  5. racenu

    racenu Well-Known Member

    Automatic or standard trans?
     
  6. DasRottweiler

    DasRottweiler -BuickAddict-

    Gonna echo what previous posters have said re: harmonic balancer, or timing chain slop/jump. Just a guess, Jim
     
  7. StagedCat

    StagedCat Platinum Level Contributor

    Maybe a broken rocker arm?
     
  8. pbr400

    pbr400 68GS400

    What ignition? I had similar symptoms a few years ago and found that two magnets had dropped out of my aftermarket ignition’s reluctor, thus no fire on those cylinders.
    Patrick
     
  9. CJay

    CJay Supercar owner Staff Member

    That was my line of thought, a miss fire.

    Dave- do you feel its an out of balance problem or an ignition misfire?
     
  10. 71Skylark1384

    71Skylark1384 Platinum Level Contributor

    Thanks for the replies. Now to try and answer some of the questions. This is a Turbo 400.
    I have not yet look at the harmonic balancer but will do this morning.

    Fan Blade looks intact but I didn't inspect it in detail. How do you know if its a broken vane in the torque converter? Do I need to pull it off? When I checked for the weight on the Flywheel/Flexplate it looked fine, no cracks I could see. The Spark plugs that are dirty/dark looking are 7 and 5. The oil pressure is good even on start up and once the engine is warm.

    I can pop the valve covers off and look at the rocker arms.

    As for the Ignition or balance problem....I can't really tell. I am not too skilled to know the difference in the vibrations. The engine itself doesn't seem to be vibrating badly enough for me to warrant the idea that the engine is causing the vibrations. But then again I could be wrong. I will pop the distributor cap off and take a look at the weights. May also pop the distributor out too and look at the gear. All of these are great ideas that I didn't even began to fathom.
     
  11. John Codman

    John Codman Platinum Level Contributor

    You say that it vibrates "even in neutral", I assume that neutral means that the car is not moving. If so, that eliminates the drivetrain except for the torque converter. Assuming that your car is the '71 Skylark in your avatar, I would (obviously with the engine running) pull each spark plug wire one at a time to determine if the vibration is cylinder specific. If you have a toolbox tachometer, the cylinder with the least RPM drop is the problem cylinder. If there is a dead or nearly dead cylinder, investigate that cylinder further (compression test, rocker arm movement, ignition issue, etc). If the vibration is not specific to one or more cylinders the issue is a rotating component. As the vibration came on suddenly, it would be logical to assume that something broke. As has been said earlier, I would take a good look at the harmonic balancer.
     
  12. gsgngregg

    gsgngregg Well-Known Member

    You can unbolt the torque converter and start it up
     
  13. CJay

    CJay Supercar owner Staff Member

    If you want to eliminate the converter from the equation, cant you take the three bolts off from the flexplate and slide the converter back into the transmission enough that it clears the flexplate?
     
  14. Briz

    Briz Founders Club Member

    Had a Olds 350 loose the rubber between the balancer hub and outer ring. It did exactly what you said. Made a heck of a noise too.
     
  15. yachtsmanbill

    yachtsmanbill Well-Known Member

    Harmonic balancer age/deterioration can always come into play. Not too sure about the outer ring slipping on the hub though. Hmmm. Aren't the two vulancized together. I had a 289 mustang that the outer ring came off and was impossible, even with a press to get back on. Now I am curious about mine having slipped. On a BBC, the balancer key at TDC #1 points directly at the top of #1 cylinder. You cant see both in the buick pics in one so Ill post both. Did the outer ring slip? Maybe thats why the timing light didnt make sense when timed Legendary Larry's way. A few other pics for kicks! The HEI housing was purchased broken just for the shaft (probably broken in transit). I am shown cutting the drive gear in the lathe for a primer rod. The drive pin is in white at the 12:00 position. ws

    IMG_5973.JPG

    IMG_5977.JPG





    IMG_6043.JPG

    IMG_6044.JPG

    z2.jpg
     
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  16. 71Skylark1384

    71Skylark1384 Platinum Level Contributor

    That is what it was. it looked weird when the engine was running. turned it off and tapped it slightly with a hammer and it moved fairly easy. So now off to get a harmonic balancer.
    Next question is Where can I get one with out breaking the bank.
     
  17. pbr400

    pbr400 68GS400

    Too bad there’s not a worldwide forum, maybe that uses the internet, that’s frequented by people who enjoy, assemble, race, repair, and vend parts for Buick engines. If there were I’d bet someone would have one.
    (Sorry, couldn’t help it). Post in ‘Parts Wanted’.
    Patrick
     
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  18. gs66

    gs66 Silver Level contributor

    Glad you found the problem. You can always get an SFI aftermarket one if you have to.
     
  19. 71Skylark1384

    71Skylark1384 Platinum Level Contributor

    thats my next step :)
     
  20. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

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