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390 cadillac rotates an inch forward and backward by hand...

Discussion in 'The Hokey Ass Message Board' started by CadillacKid, Sep 20, 2013.

  1. CadillacKid
    Joined: Oct 15, 2002
    Posts: 1,507

    CadillacKid
    Member

    Okay fellas...this may sound like a stupid question, but I was working on my '59 Cadillac tonight and when I leaned on the power steering pump pulley, the belt moved...I grabbed a light for a closer look, and I noticed the crank pulley and balancer moved too...I can move all of the pulleys back and forth about an inch by hand...I know this isn't good, and I've put ALOT of miles on the car since the rebuild of the engine...sound like a timing chain that's worn out to y'all? It starts right up by the way...but I have noticed it developing an intermittent miss lately...
     
  2. cmyhtrod
    Joined: Nov 29, 2008
    Posts: 360

    cmyhtrod
    Member
    from ct

    Sounds like timing chain to me
     
  3. txturbo
    Joined: Oct 23, 2009
    Posts: 1,771

    txturbo
    Member

    Is the actual crankshaft turning with the pulleys? If not, you may just have a bad harmonic balancer.


    Posted using the Full Custom H.A.M.B. App!
     
  4. Tedd
    Joined: Jul 7, 2007
    Posts: 118

    Tedd
    Member

    Loose damper?
     

  5. Kirk Hanning
    Joined: Feb 27, 2005
    Posts: 1,603

    Kirk Hanning
    Member

    I second the wow
     
  6. #1 Make sure the actual Crank shaft is moving with the Dampner.

    #2 Lift the dist cap and watch the rotor .
    If the rotor isn't moving at all and the crank is, put in a new timing chain right away.

    The Wizzard
     

  7. X2 loose damper/crank pulley
     
  8. Crank shaft has a 3/16 keyway in it. It would have had to sheer the key to have that much movement. If the damper is that loose on the crank it would have chucked the 1/2" bolt holding things together.
    The Wizzard
     
  9. CadillacKid
    Joined: Oct 15, 2002
    Posts: 1,507

    CadillacKid
    Member

    Yes, that was my thoughts exactly in regards to the keyway and the 1/2" bolt...gotta be the timing chain...I really thought about it, and it seems to me I put the last timing chain in that engine about 200,000 miles ago...and that would also explain the intermittent miss I keep getting, and she's been running 5 to 10 degrees hotter than she used to also...thanks for the opinions fellas :)
     
  10. FLAT6
    Joined: Dec 15, 2003
    Posts: 386

    FLAT6
    Member

    Just a thought, keys are generally only used to provide indexing of components relative to each other, not as a positive torque driving mechanism (obviously some gear trains rely solely on keys, but those are generally low torque). The high torque on a crank pulley/damper bolt (with a slight interference fit in some cases) is what provides the torque transfer for the belt driven accessories. Keep in mind that the clamping force of that 1/2" bolt at 100ft-lbs is 12000lbs of clamping force with a nominal friction co-efficient of 0.25 for mating steel surfaces yields 3000lbs of friction force. This is why it is so important to properly torque the damper and not just rely on the key.

    Also, if it was the timing chain slack causing the issue, I would be more concerned at how easily you can rotate the crank/piston assy with the ring friction and compression working against you.
     
  11. Easy rotation ???
    Try working 200,000 miles onto the thoughts.

    This is a 45 seconds flat diagnosis for sloppy timing chain.
    Pop the distributor cap.
    Move crank and look for the rotor to follow.
    If you can move the crank an inch and the rotor doesn't move your chain is stretched.
    Just make sure it is the crank that is turning.
     
  12. FLAT6
    Joined: Dec 15, 2003
    Posts: 386

    FLAT6
    Member

    Definitely not debating that the cam chain might not be stretched, but 200,000 miles doesn't bother me too much

    I would wager that you could take a 200,000 mile engine and pull the heads off (i.e. no valve train resistance or compression resistance), then try to spin the crank/pistons by "leaning" on the power steering pump and you wouldn't be able to easily spin it over without actually trying to

    My post was mostly just giving some input on the key and damper relationship
     

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