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need help with f head rod bearing

Discussion in 'Early CJ5 and CJ6 Tech' started by nitrohemi, Jul 31, 2005.

  1. Jul 31, 2005
    nitrohemi

    nitrohemi New Member

    marietta PA
    Joined:
    Dec 7, 2004
    Messages:
    23
    I had a problem with my number one rod bearing in that it wore out with only about a few hours on the motor. I replaced it and it ran fine for ablout another hour. then after I went arounf the block I started it the next day and it was fine. turned it off after a few seconds. fiddle with the carb. tried to start it again and it cranked real slow like something was holding it up. then notheing. it see,s as if it is looked up. If I spun thre number one rod bearing would it lock the mort up? and what is the problem here. this is the second bearing to do it in just a trip around the block. the original rod bearing was chewed up pretty good when I rebuilt the motor. I have yet to take the oil pan back off to see if the rod bearing is definatly screwed up and locked the motor up. probably will do that this week. any ideas would be greatly appreciated.
     
    nitrohemi, Jul 31, 2005
    #1
  2. Jul 31, 2005
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
    Joined:
    Sep 20, 2002
    Messages:
    4,350
    Which way is the oil hole in the rod facing?
     
    blevisay, Jul 31, 2005
    #2
  3. Jul 31, 2005
    nitrohemi

    nitrohemi New Member

    marietta PA
    Joined:
    Dec 7, 2004
    Messages:
    23
    I know all the stamped numbers on all the rods are pointed to the same side. wich ever side the manual calls for. I thought maybe I put the piston and rod in the wrong way when the first rod bearing got wiped out
     
    nitrohemi, Jul 31, 2005
    #3
  4. Jul 31, 2005
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
    Joined:
    Sep 20, 2002
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    4,350
    I would Plastiguage the bearing


    [​IMG]


    Dunno if this helps.......I will keep thinking :hurrican:
     
    blevisay, Jul 31, 2005
    #4
  5. Jul 31, 2005
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
    Joined:
    Sep 20, 2002
    Messages:
    4,350
    [​IMG]
     
    blevisay, Jul 31, 2005
    #5
  6. Jul 31, 2005
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
    Joined:
    Sep 21, 2002
    Messages:
    12,378
    Oil gallery plugged? What kind of oil pressure did you have?
     
    Glenn, Jul 31, 2005
    #6
  7. Jul 31, 2005
    Mcruff

    Mcruff Earlycj5 Machinist

    Albertville, AL
    Joined:
    Sep 22, 2002
    Messages:
    5,349
    Billy said:
    I would definately plastigage the bearing, check to make sure the bearing is in the right way and you have good oil pressure.
    How much of an engine rebuild did you do, was it a complete rebuild. Did you check the diameter on the rod journal to make sure it was stock size and it didn't have an oversized journal and you replaced it with a bearing that didn't fit right.
     
    Mcruff, Jul 31, 2005
    #7
  8. Jul 31, 2005
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
    Joined:
    Nov 6, 2002
    Messages:
    4,275
    It's also *REALLY* easy to nick the crank journal when reinstalling the rod/piston combinations. It doesn't take much of a nick to trash the bearing, since even a tiny dimple on the polished surface will raise the metal up around the divot. I found this out the hard way when I rebuilt my old Mopar 340 and I destroyed an expensive forged crank. :mad:

    You can use either a pair of old straight spark plug boots or some rubber fuel line over the rod bolts to protect the crank journals when reassembling things.

    IMHO I'd pull that crank and have it machined before I'd waste any more time or money on it.
     
    w3srl, Jul 31, 2005
    #8
  9. Aug 1, 2005
    Posimoto

    Posimoto Hopeless JEEP Addict

    Minden, Nevada
    Joined:
    Aug 7, 2003
    Messages:
    4,538
    Did you thoroughly clean the crank before you put it in? Blow out all the oil passages in it? I seized up a 4 banger on my first rebuild because I assumed when I took that shiny (apparently clean) crank out of the box it was good to go. They aren't. When I got the replacement crank I cleaned out a ton of filings frim inside the oil passages. That's what caused the first one to weld the #4 bearing to it.
     
    Posimoto, Aug 1, 2005
    #9
  10. Aug 1, 2005
    nitrohemi

    nitrohemi New Member

    marietta PA
    Joined:
    Dec 7, 2004
    Messages:
    23
    motor had good oil preussure. I think I will see what size the crank is and see if it us still useable. I did a ring and bearing rebuild on it when I previuosly rebuilt it a few months ago. rebuilt some big block mopars but nothing like this has ever happened. I was tryting to prevent puloling the motor again but to put a new crank in I will have too. I will update you guys when I get the oil pan off to check things out.
     
    nitrohemi, Aug 1, 2005
    #10
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