Is it dangerous - cracked flexplate on a Northstar
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Northstar Engines and System Technical Discussion Discussion, Is it dangerous - cracked flexplate on a Northstar in Cadillac Engine Technical Discussion; I just recently found out that my 01 Deville has a crack or loose fly wheel. Is there a easy ...
  1. #1
    mariojacksonjr is offline Cadillac Owners Member
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    Is it dangerous - cracked flexplate on a Northstar

    I just recently found out that my 01 Deville has a crack or loose fly wheel. Is there a easy way to tell if its cracked or just loose? And how dangerous is it to drive the car..until its fixed? Lastly...can you just disconnect the transmission or do u have to pull the engine

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    Submariner409's Avatar
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    Re: Is it dangerous

    Dangerous and expensive. A cracked flexplate can cause extensive engine and transmission damage. The entire drivetrain cradle, including front suspension, needs to be lowered, the transmission and torque converter removed, and the flexplate replaced. For a 2001 Deville, regardless of mileage, a new torque converter and the TCC operating solenoid should be replaced at the same time.

    EDIT: This echoes your duplicate post (closed thread) up in Deville.

  4. #3
    mariojacksonjr is offline Cadillac Owners Member
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    Would I still have to replace it even if its just loose because of it not being tighten up when the new engine was put in?

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    Re: Is it dangerous - cracked flexplate on a Northstar

    I've never heard of a loose one, but if that's the case and it is not damaged, then you could reuse it. Why do you suspect it is cracked or loose?

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    Re: Is it dangerous - cracked flexplate on a Northstar

    If it's loose and rattling around - either the flexplate and/or the torque converter - the bolts and bolt holes will be ruined from the slop.

    The threaded bolt holes in the crank flange should be OK, but the flexplate bolts and holes will be ruined; same scenario if it's a loose torque converter.

    There were a couple of threads here a few years back with some pretty graphic pictures of a Northstar flexplate that had lost the entire center circle.

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    Re: Is it dangerous - cracked flexplate on a Northstar

    97EldoCoupe likes this.

  8. #7
    Submariner409's Avatar
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    Re: Is it dangerous - cracked flexplate on a Northstar

    Aw, shucks ........ A little JB Weld and that's good to go.
    97EldoCoupe and Speedygman like this.

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    Speedygman is offline Cadillac Owners Fanatic
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    Re: Is it dangerous - cracked flexplate on a Northstar

    The Navy way is the best way?

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    Submariner409's Avatar
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    Re: Is it dangerous - cracked flexplate on a Northstar

    Nah - no epoxies or exotics - we always used a gray, sticky putty called "Duct Seal" today - we called it "Monkey shit" in the 60's.

  11. #10
    the recluse is offline Cadillac Owners Connoisseur
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    Re: Is it dangerous - cracked flexplate on a Northstar

    Monkey shit is grey?

    Must be a really old monkey...

    To OP, think of it this way...your driving own the road and feel the need to pass the little old lady in front of you...for various reasons, topmost being that she's slow...you put your foot to the floor and peak out at about 6,000 rpm's, aaannnnddd the flex plate lets go...along with half the trans housing, the back end of the engine, the torque convertor, the dust cover, half the oil pan, the wiring harnesses that live in the general area, as well as all the fluid contents of the aforementioned.

    The blinding smoke and cavelcading shrapnel causes said little old lady to freak out and wind up in a ditch...

    so yes, it's possibly dangerous...

    As a side note, are you sure it's not just exhaust rattling from the crossover pipe?

  12. #11
    stoveguyy is offline Cadillac Owners Connoisseur
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    Remove engine or remove trans?
    I think a trans shop could yank the trans easier than garage pulling motor
    U need to get trans out of way to figure out if flex plate bolts are good/bad

  13. #12
    Caddy-EaRL's Avatar
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    Engine removal and trans removal is the same procedure until the subframe with both units is lowered. You then remove the engine or trans.

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    stoveguyy is offline Cadillac Owners Connoisseur
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    U can pull motor out the top. And leave subframe alone. Pull motor does not mean drop motor/trans assy unless u say so

  15. #14
    Caddy-EaRL's Avatar
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    Quote Originally Posted by stoveguyy
    Remove engine or remove trans?
    I think a trans shop could yank the trans easier than garage pulling motor
    U need to get trans out of way to figure out if flex plate bolts are good/bad
    Quote Originally Posted by Caddy-EaRL
    Engine removal and trans removal is the same procedure until the subframe with both units is lowered. You then remove the engine or trans.
    Quote Originally Posted by stoveguyy
    U can pull motor out the top. And leave subframe alone. Pull motor does not mean drop motor/trans assy unless u say so

    What does pulling the engine from the top have to do with the procedure for pulling the transmission?

  16. #15
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    Re: Is it dangerous - cracked flexplate on a Northstar

    here at Northstar Performance, we do have brand new flex plate for $75 + Shipping, and yes they can loosen up especially if you use down shifting to assist your stopping. give Jake a call at 888-800-9470, or email him at info@northstarperformance.com

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    as well as if you remove the flex plates bolts remember to re-silicone the bolts due to the bolt holes protrude all the way through the end of the crank that would cause it to leak oil if put in dry
    97EldoCoupe likes this.
    Replacing the Head Gaskets on a Northstar? Use our SureGrip Cylinder Head Stud Kit!


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