1. Aarons Air

    Aarons Air Well-Known Member

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    I've been restoring my 68 coronet for the last few years. A couple of years ago i bought a freshly rebuilt 64 block 383 motor to put in it. The motor was close to stock, with the exception of a mopar purple cam, and a few bolt ons. I dropped the motor in about a year ago. I bolted the motor plate to the flywheel, but haven't done anything else to it since. As i have been working on the rest of the car.
    So a few days ago i added 5 qts of oil and a bottle of lucas break in zinc additive. Then i pulled the dist & intermediate shaft, and primed the oil pump. Next i put a socket & breaker bar on the crank bolt , to turn it by hand. The engine turned just slightly and then felt like it was steel jammed against steel. And wouldnt turn any further, even with considerable force. I turned the ratchet backward a few clicks( less than one full rotation), and it seemed to be moving ok. But as soon as i go forward again, and reach the same spot, it binds up again.
    I pulled the valve covers but saw no signs of bent rods, broken springs etc. Next i sprayed wd40 in the spark plug holes and tried turning it back n forth. It pushed the wd40 out of some of the plug holes, but stopped rotating again at the same spot.
    The car is an automatic. And the trans was rebuilt before installing. Theres no trans fluid in the trans yet, but i did check that it was in park ( tried nueteal too).
    Could this be a seized piston, stuck valve, or stuck lifter ? Or a clearance problem with the rotating assembly ?
     
  2. Stanton

    Stanton Well-Known Member

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    So did you ever turn the motor over before now ???

    If the motor will go almost a full rotation I'd say there's a nut or something fallen in one cylinder.

    If it only rotates about a half turn then I'm thinking a damaged bore and it stops at the same spot in either direction. But the fact it turns some leads me to believe its only one bore.

    I think at least one head has to come off to start. Whether you pull the right one is a 50/50 chance. But if its a rust damaged bore then it all has to come apart anyway. You may be able to clean up the bore(s) but chances are the rings are junk.
     
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    • 1967coronet

      1967coronet FBBO Gold Member FBBO Gold Member

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      { I bolted the motor plate to the flywheel } Flex plate to Converter ?
      I would start checking for a odd or to long of a bolt someplace. It happens.
      Unbolt the flex plate from the converter , make sure you dont have a odd flex plate bolt in the crank flange.

      Nothing out of place there, back off your rocker shaft retain bolts and pull them, try again.

      if needed drain oil and drop the pan and watch while a buddy turns the crank.
      Hope its something simple. :thumbsup:
       
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      • Tinker67

        Tinker67 New Member

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        This may sound just wrong , but are all four flex plate bolts in place and torqued? I had that happen once, trying to multi task to many things at one time.
         
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        • 4mulas

          4mulas Well-Known Member

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          Do everything he says here in order
           
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          • Aarons Air

            Aarons Air Well-Known Member

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            Yes, theyre in and torqued.i used thread lock too.
             
          • Aarons Air

            Aarons Air Well-Known Member

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            Thanks for the insight. This may be a dumb question but once i unbolt the flex plate should i be able to rotate the engine without any concern that the trans parts are hitting anywhere ?
             
          • 4mulas

            4mulas Well-Known Member

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            Yes, providing nothing wrong in the motor. He wants you to unbolt the flex plate because 9if you put too long of a bolt in any one of the holes it may be sticking through the other side and hitting the block preventing it from turning.

            Do things in the order 67 coronet recommended
             
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            • bearman

              bearman FBBO Gold Member FBBO Gold Member

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              Follow the steps above power of limitations will be best. Good luck hoping for a positive outcome.
               
            • 1967coronet

              1967coronet FBBO Gold Member FBBO Gold Member

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              Yes , unbolt the flex plate from the converter.
              also take a light and look up to the crank flange and just see if all the bolts that hold the flex plate to it have clearance on the back.
              may need a light and mirror for that.
              This is a auto trans car right ?
               
            • beanhead

              beanhead Well-Known Member

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              Yes double-check all your bolts and anything that could interfere first. "I" would then remove all accessory belts and unbolt it from the torque converter and gently try again, to rule out anything outside the engine. If the problem persists, squirt something like Marvel Mystery Oil into the spark plug holes, gently work the engine back and forth a bit to help distribute the oil, and then let it soak; then gently try again. May have developed a rust spot in one of the cylinders. If it still gets stuck, I'd be pulling the rocker gear, then gently trying again..to rule out valve-to-piston interference. This unfortunately sounds like the aftermarket cam isn't in properly, or is too big for the piston height/type. If you don't know which cam is in there, or how high up the pistons are traveling (or if they have good valve reliefs) that can getcha in trouble real quick. If pulling the valvetrain doesn't solve it, pull the intake and look in the valley for a problem. If that checks out, I'd pull the heads:( and look in the bores. Take a systematic approach=easy stuff first..good luck!
               
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              • Aarons Air

                Aarons Air Well-Known Member

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                Auto trans -yes
                 
              • Don Frelier

                Don Frelier FBBO Gold Member FBBO Gold Member

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                It's not hydo-locked? How much WD-40?
                If you unbolt the rocker shafts you need to have all the plugs out since the valves are closed you have total compression everywhere.
                Piston hitting a head?
                 
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                • Aarons Air

                  Aarons Air Well-Known Member

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                  No, its not hydro locked. I sprayed maybe an ounce or two in each cylinder. And a lot of it was pushed out of the plug holes when i partially turned it.
                   
                • Fran Blacker

                  Fran Blacker FBBO Gold Member FBBO Gold Member

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                  Before pulling head(s) a scope attached to your phone? Valve stuck open. Many good suggestions.
                   
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                  • bearman

                    bearman FBBO Gold Member FBBO Gold Member

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                    Do you have a camera or does one of your friends. If you do look in each cyn hole maybe see valve piston touching.
                     
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                    • slimt

                      slimt FBBO Gold Member FBBO Gold Member

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                      Lots of valuable info here. Ill be saving this thread.
                       
                    • Ernie ingling

                      Ernie ingling Well-Known Member

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                      :popcorn:
                       
                    • Robert Schaad

                      Robert Schaad Well-Known Member

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                      I have had this happen several times. I did not completely tighten one of the Torque converter bolts. I also bought a 360 with 727 that the seller told me was locked up. Same problem, one torque bold was lose and hit the block and stopped the turning of the engine. Tightened up bold and engine ran. Takes very little time to check it. Just my experience.
                       
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                      • Aarons Air

                        Aarons Air Well-Known Member

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                        Just removed the 4 torque converter bolts. Still won't turn. With this style of flex plate, i can't really see the crank flange bolts.

                        20191229_155030.jpg
                         
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