Change the rod bearings and cross your fingers!

Small Block Mopar Engine

Should I ....

  1. Change the bearings and cross my fingers

    5 vote(s)
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  2. Build another engine

    0 vote(s)
    0.0%
  3. Try some straight 50 and use ear plugs till I'm broke down on the side of the road somewhere

    2 vote(s)
    20.0%
  4. Light it on fire and roast hotdogs over the flames.

    3 vote(s)
    30.0%
  1. MOPAROFFICIAL

    MOPAROFFICIAL FABO Gold Member FABO Gold Member

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    So I have a 96 360 magnum that got some ported heads that were also a few cc smaller bumping up the squeeze... so after a few thousand it sounds like a slight rod knock 'pass side'. Its faint.... so I'm thinking about pulling the oil pan and changing A. The rod bearings and B. The oil pump. It's a crap shoot I know but the odds are slightly in favor I believe... but I could be wrong. Have to see what the journal looks like.
    Should I or should I just build another..
    What say you guys?
     
  2. Jadaharabi

    Jadaharabi FABO Gold Member FABO Gold Member

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    Pull the pan and check the bearings.
     
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    • TT5.9mag

      TT5.9mag Two atmospheres are better than one

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      What has happened with the oil pressure in those few thousand? Any change?
       
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      • Garrett Ellison

        Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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        Mic the journal to see how far out of round it is. Maybe try going with a few thousandths undersize bearing or just the top shells of an undersize set and regular size shells in the bottom to tighten the clearance marginally.
         
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        • Dana67Dart

          Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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          Someone (not me) came home from a 40mile drive and informed me that the car sounded like a sewing machine the whole way home.

          Not enough oil to pump up the lifters.

          The engine had 60,000 miles on it.

          Put a bottle of slick 50 in and the rest with oil.

          For the next 100,000 miles it had a deep thunk, (rod knock)

          Only stopped driving the car when I couldn't get the auto trans to shift into druve anymore, reverse was fine.

          Moral to the story...

          All you have to loose is time and a few bucks.
           
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          • 1WildRT

            1WildRT Well-Known Member

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            If the journal isn't scored & mics out okay throw bearings in it & roll the dice...
             
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            • Garrett Ellison

              Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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              The high volume oil pump (with an adequate oil pump drive) probably won’t hurt anything either.
               
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              • eekvonzipper

                eekvonzipper My Member is Legendary! FABO Gold Member

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                Ask Uncle Tony! He'll Know What To Do!! :poke:
                 
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                • George Jets

                  George Jets 1967 Dart 2 Door FABO Gold Member

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                  Rods and mains and a new std oil pump will bring the oil pressure up.

                  Hand polish the affected journal as long as it's not totally gone. Have used small high density Foam plugs to keep the crap out of the crank oil gallies when polishing the crank in the vehicle. Remember to take them out when finished with the polishing.

                  WD-40 and some 240 wet dry strips work pretty good, can follup with some crocus cloth if you want.

                  Before:
                  Can see my high density foam plug in the crank here.
                  20200719_194721.jpg
                  After :
                  Most of the time it is bearing material that has transferred to the crankshaft making it look worse than it is. A light polish will remove that bearing material and clean it up nice again.

                  Screenshot_20210415-180436_Gallery.jpg
                   
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                  • George Jets

                    George Jets 1967 Dart 2 Door FABO Gold Member

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                    The main bearings take a beating on the bottom halves, so if you pull a main cap and it looks good the mains may be OK. Like to change them too if you can, gets a little hard to do the top half thrust bearing in the vehicle with crank still in.
                     
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                    • Oldmanmopar

                      Oldmanmopar Going left turning right FABO Gold Member

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                      You said the knock is on one side? At the head area? Does it go away under a load? How is the oil pressure? Had a 340 knock at idle and when ever decelerating but went away under a load It was a bad piston pin hole. It too was on one side under the hood. Usually a bearing is lower and can be heard coming from the pan.

                      Unless you have a spun bearing and both are in the rod? Then the piston could be hitting the head. Pull the plug wires one at a time while idling to locate the cylinder if its a pin you'll hear it. If the oil pressure is real low then you know its a bearing and I wouldn't run it.

                      Also had one come here and he dropped a carb nut down and it was squashed/molded into a piston. knocked like crazy
                       
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                      • MOPAROFFICIAL

                        MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                        Nope. Seems the same. Just that light knock at cold start
                         
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                        • MOPAROFFICIAL

                          MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                          I just want to point this out to the site that this is my own thread and I have received only one notification for it out of all the responses it's gotten. This happens a lot.
                           
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                          • MOPAROFFICIAL

                            MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                            I dont want to the intermediate drive out for another if I can help it.
                             
                          • MOPAROFFICIAL

                            MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                            Did that on a 390 fe, along with the rod bearings. Works
                             
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                            • TT5.9mag

                              TT5.9mag Two atmospheres are better than one

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                              That’s odd. But I’ve noticed it happening to me also once in a while. I’ll go back to a watched thread and it’s 2 pages longer with no alerts.
                               
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                              • TT5.9mag

                                TT5.9mag Two atmospheres are better than one

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                                How many miles on the bottom end? Stock?
                                 
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                                • 74Scooter

                                  74Scooter Well-Known Member

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                                  Could work... tried slightly thicker oil as troubleshooting?
                                   
                                • 74Scooter

                                  74Scooter Well-Known Member

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                                  Did you do this with the motor still in the car? Pretty much anything (aside from trucks) Ford stuffed an FE into they did with a shoe horn. It's not even possible for me to drop & remove the pan on mine without loosening the mounts and lifting the entire enchilada.
                                   
                                • Bobzilla

                                  Bobzilla Well-Known Member

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                                  The 5.9 Magnum in my 1999 2500 pickup tore up a rod bearing right around 85,000 miles on the odometer, and likely caused by me driving too fast in third gear on the freeway with a trailer that was too heavy.

                                  Mine was most noticeable in park and lightly raising the rpm. Isolated the cylinder as oldmanmopar said, by pulling a plug wire off and revving it again. Noise was not heard with plug wire removed from the bad cylinder.

                                  I took the oil pan off hoping to replace the bearing but it was a waste of time. Once I could hear the noise the crank journal was already trashed. Badly scored and undersized.

                                  Do some testing, but know that if it is a rod bearing you should expect to need the crankshaft ground and new bearings. But definitely worth fixing it.
                                   
                                • mygasser

                                  mygasser FABO Gold Member FABO Gold Member

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                                  if it's mainly when cold and the oil pressure's fine it could be piston 'slap', when the pistons warm and expand they quiet down. i've had that before.
                                   
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