M42 crank hard to turn over by hand

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  • givemeaboost
    Noobie
    • Jul 2014
    • 25

    #1

    M42 crank hard to turn over by hand

    Hey guys, so today i threw a head on my m42. prior to this I did some block work including new rod bearing and main bearings, also bored out the cylinders to 86mm to fit bigger pistons. The crank and pistons moved freely with the head on but as soon as i hooked up the timing chain its a bitch to move. All the timing is set to tdc as well. I can put some good force on it to get the crank to move slightly but it seems way to hard for it to be normal. Btw the cams were exposed inside the head for about a month before this would that have some cause for it
  • bmwman91
    No R3VLimiter
    • Oct 2004
    • 3128

    #2
    A moderate increase in the torque required to turn the crank by hand is expected when putting the timing chain on with the head, but it should not feel overwhelmingly difficult. I would check to make sure that the cams and crank are not 180 degrees out of phase. When you say all is at TDC, you mean that cylinder 1 is all the way up and the cam loves for #1 are pointing "up & in"?

    Transaction Feedback: LINK

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    • e30davie
      E30 Mastermind
      • Apr 2016
      • 1788

      #3
      Had the head checked for bent ness? If the head was overheated it might be bent, and now the camshaft doesn't spin like it should.

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      • givemeaboost
        Noobie
        • Jul 2014
        • 25

        #4
        Originally posted by bmwman91
        A moderate increase in the torque required to turn the crank by hand is expected when putting the timing chain on with the head, but it should not feel overwhelmingly difficult. I would check to make sure that the cams and crank are not 180 degrees out of phase. When you say all is at TDC, you mean that cylinder 1 is all the way up and the cam loves for #1 are pointing "up & in"?
        Yes that is correct the cams lobes are facing each other in a 45 degree angle like they should and the pistons are up in cylinder 1

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        • givemeaboost
          Noobie
          • Jul 2014
          • 25

          #5
          Originally posted by e30davie
          Had the head checked for bent ness? If the head was overheated it might be bent, and now the camshaft doesn't spin like it should.
          Cams were spinning free upon removal though

          Comment

          • bmwman91
            No R3VLimiter
            • Oct 2004
            • 3128

            #6
            Are you turning the crank in the proper direction (normal engine rotation direction)? Trying to turn it backwards will often cause the chain to disengage the crank sprocket and get jammed up in the lower guide.

            Transaction Feedback: LINK

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            • givemeaboost
              Noobie
              • Jul 2014
              • 25

              #7
              Originally posted by bmwman91
              Are you turning the crank in the proper direction (normal engine rotation direction)? Trying to turn it backwards will often cause the chain to disengage the crank sprocket and get jammed up in the lower guide.
              yes turning the engine clockwise

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              • givemeaboost
                Noobie
                • Jul 2014
                • 25

                #8
                got the cams to move . ended up the chain was binding up on the idle sprocket, thanks for all the replys

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