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Discussion in 'Early CJ5 and CJ6 Tech' started by Howard Eisenhauer, Jun 30, 2015.

  1. Jul 2, 2015
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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  2. Jul 2, 2015
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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    Yeah, I've only read about the front bearing failure due to the timing gear nozzle, but I figured I'd toss that idea out.
     
  3. Jul 2, 2015
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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    Babbitt is poured, and has a low melting point. I know they use it in big compressors and such. I should have read the link first. Since it's used in modern bearings still I guess the melting point isn't as low as what I was told. Interesting.
     
    Last edited: Jul 2, 2015
  4. Jul 2, 2015
    oldtime

    oldtime oldtime

    St. Charles,...
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    Sad times for sure but don't let it get to you Howard.
    Looks to me like a very small foreign particle got under the bearing shell and that's what scored the babbit.
    Likely was from debris that was left up inside the oil gallery.

    I think you should fully remove the crank and try to polish out that rear main journal.

    In other words its best to rebuild and re-clean your rebuilt engine.
    Don't pull the pistons out as they are probably O.K.
    Best to to re-clean out the oil gallery and all oil ports.
    Figure on a new set of gaskets and all new main bearings.

    You certainly did the right thing by tearing into it the way you did.
     
  5. Jul 2, 2015
    Alan28

    Alan28 Well-Known Member Sponsor 2019 Sponsor

    Ch√Ętillon en...
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    That is horrible.
    It happened to me, and to many others I suppose.:beer::beer:
    Have a good meal, discuss with friends of something else.
    My suggestion is :
    Put your Jeep in your garage and wait some days to feel better and decide something.
    Forget this event. You have an other car.
    maybe you will find something in the oil when emptying the engine.
    You don't know yet. Wait a little bit, this is not your health or someone with a problem in your family.mehh
     
  6. Jul 2, 2015
    chipdom

    chipdom Member

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    Back in 1979 when I was just a kid I had a 1968 Camaro RS/SS with a 375 HP 396ci and had a trade school (pro) do a rebuild and watched him moly coat both sides of the bearings. I questioned him with common sense and he said he did it on his 427 Chevelle. Anyway he got it running and the engine failed miserably. It seems one of the bearings spun slightly on startup and closed the oil passage and the wheels just locked up on the road when the bearings siezed. One of my worst days, that car took most all my money and then some. Sorry to hear your story, I know the feeling.
     
  7. Jul 2, 2015
    windyhill

    windyhill Sponsor Sponsor

    PA
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    Hang in there Howard!
     
  8. Jul 7, 2015
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

    Tantallon, Nova...
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    Expert Opinions required-

    Is a digital caliper good enough to measure journal diameter or is a micrometer required?

    I've got a spare crankshaft that I believe has never been worked on- no obvious scratches/marks on it so I think it just needs a (very) little polishing to remove some discoloration but before I order a set of bearings I need to verify it's within spec.

    H.
     
  9. Jul 7, 2015
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
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    Last edited: Jul 7, 2015
  10. Jul 7, 2015
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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    Micrometer is the right answer.
    But as a shade-tree amateur I have managed to do all my work with dial calipers and plastigage.
     
  11. Jul 7, 2015
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

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    JMO - you'd be better off with the Import mic shown in the Enco link than calipers. Ca $20. No personal experience - maybe an expert could comment. I would use Plastigage regardless.
     
  12. Jul 7, 2015
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
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    I have been scolded by some for using calipers to measure journal diameters and not using a micrometer. I have gotten by with calipers and not micrometers for measuring journal diameters and my engine runs fine. I have since happened to own sets of calipers and when i measure using 3 sets of calipers and 2 different micrometers on the same part, the only variation i got in measurement was operator error. You're looking to see if it has been worked on, not welding and grinding bad journals yourself. Plasiguage works for just about everyone and thats not a science, what with the chart they give you.

    I use a 9 dollar HF digital chinese caliper. gets me close enough. I don't do it for a living.

    I am sorry about your scored journal. It is fully repairable though.
     
  13. Jul 7, 2015
    tarry99

    tarry99 Member Sponsor

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    Ever walk into a Crank grinding shop and see them pull out there HF calipers to measure a journal? I don't think so! ........Understanding the correct size and the related bearing clearance is important to your motors life.........being off just one thousands in clearance can make the difference between how much oil pressure you will have. Get a micrometer and measure it.
     
  14. Jul 7, 2015
    oldtime

    oldtime oldtime

    St. Charles,...
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    Anyone who can properly polish the crank will have a good micrometer.
    The proper micrometers will read tolerances of .0005, half thousandth or less.
    They are typically polished with 400 grit belts.
     
  15. Jul 7, 2015
    47v6

    47v6 junk wrecker! Sponsor

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    This is my point. Also plastiguage is not a substitute for a micrometer and yet people use it every day to check clearance and somehow it works.
     
  16. Jul 7, 2015
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

    Tantallon, Nova...
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    Thanks for the input folks but I won't be buying any mikes- I'd need two different sizes to check both the main & rod journals plus there's none available locally above 2". Plus this is the only thing I'd ever use them for.

    If the caliper won't do it then it's off to the machine shop for the work which is extra time & money :(

    I *might* be able to polish the damaged crank but I'd still have to verify the diameter afterwards. According to what's stamped on the bearing shell it's already 20 thou down, next step would be 30 thou :)eek:$$$) plus I still haven't checked the rod journals- I won't be surprised if some crud made it's way up into #4.

    H.
     
  17. Jul 7, 2015
    oldtime

    oldtime oldtime

    St. Charles,...
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    I get by with a simple old fashion but high quality stainless vernier calipers. +or - .001"
    They have served me well and without error since the late 1970's.

    I'm not doing my own crank polishing.
    I leave that up to the man who can afford the correct tools for the job.
    When you have all those required tools you generally go into that as an occupation.
    My jeep hobby is certainly not an occupation.
    An occupation would tend to take some of the fun out of it. Ha !

    Crank polishing is inexpensive.
    Crank grinding is typically up around $240
     
    Last edited: Jul 7, 2015
  18. Jul 7, 2015
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

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    Plastigage is "defense in depth." Aside from being cheap, its main advantage is that it's a way to measure the bearing clearance with the crank assembled completely separate from the "actual" measurement of the journals and in-place bearings with micrometers. Heaven forbid you incorrectly read your measurement tools, you have this additional check.
     
    Last edited: Jul 7, 2015
  19. Jul 7, 2015
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

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    Enco -

    http://www.use-enco.com/CGI/INPDFF?PMPAGE=315&PMCTLG=00

    PN 600-0012 1-2" outside micrometer, 0.0001" graduation, $14.01
    PN 600-0013 2-3" outside micrometer, 0.0001" graduation, $10.15
    PN 600-003 0-3" outside micrometer set, 0.0001" graduation, $36.54

    Gotta be better than the HF caliper. Cheap insurance.

    Even if I sent the crank out to a shop, I would check the work both with micrometers and Plastigage. Mistakes happen, and there's no one more motivated to get it right than you. Measure measure measure.
     
    Last edited: Jul 7, 2015
  20. Jul 7, 2015
    45es

    45es Member Sponsor 2019 Sponsor

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    As all of us, I am sorry for what happened and also curious as to one question that has not been answered. You said, "This thing was "professionally" rebuilt & I checked the mains clearances myself- they were all 2 - 2.5 thousands." This statement to me seems to indicate the shop did the machine work properly and to spec. What it doesn't say is if the shop's procedural steps were followed. Was the block thoroughly cleaned after all of the machine work was complete? Were the oil passages cleaned and checked? What feedback did you receive from your professional rebuilder?

    At the very least, I would expect the polishing of your replacement crank would be provided at no cost to you by this shop if that is the route you choose to go.
     

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