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Thread: 3.0l 4JH1 engine rebuild

  1. #1
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    3.0l 4JH1 engine rebuild

    I am rebuilding a 3.0l 4JH1 engine for a landy conversion. I acquired a non running engine to see if it is rebuildable. It came from a 2004 NKR 200 truck and was described as seized.


    Taking the head off, #3 piston was free and could be removed to reveal the bearing cap missing and a damaged big end bearing. With the bottom end now stripped down, big end bearings #2 & 3 are scored plus at least one main bearing. The missing conrod cap and bolts were in the sump. Apart from scored shells, the conrod, cap, piston, bore and bolts appear undamaged!


    I would expect that if the conrod bolts came out during service then all hell would break loose in terms of crank-conrod contact, or necked bolts etc. There is nothing. A few of the sump bolts were loose, so maybe it was inspected before it catastrophically failed?


    What are the symptoms of multiple bearing failure? Screaming noise? Enough to stop before catastrophic failure?


    So on from here. These cranks appear to be not regrindable. I have a lead on a replacement 2nd hand crank. Obviously new shells required throughout. The manual says the bores should not be rehoned. Should I replace the rings whilst here?


    Another issue may be flushing everything to get rid of the chrome flakes about the place?


    I'd value your advice.


    Chris


    2014 D4 TDV6
    1954 86" (I'll finish it one day.....)
    1980 Stage 1 v8

  2. #2
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    I'd start with crack testing. A flailing conrod can do lots of damage.
    I don't suppose you have a chance to talk to whoever was driving it at the time- would be nice to know what actually happened.
    Various people have their own opinions, but I've generally found Isuzu motors to be pretty solid. They're not at all fond of prolonged idling, though.
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  3. #3
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    Quote Originally Posted by donh54 View Post
    I'd start with crack testing. A flailing conrod can do lots of damage.
    I don't suppose you have a chance to talk to whoever was driving it at the time- would be nice to know what actually happened.
    Various people have their own opinions, but I've generally found Isuzu motors to be pretty solid. They're not at all fond of prolonged idling, though.
    No chance of speaking to the previous owner unfortunately. Its been owner->wrecker->me.
    The more I think about it, it must have been making unhealthy noises, so someone has taken off the sump to have a look, found the stuffed bearings, then just thrown the cap and bolts in the sump and put it back together and written off the truck. If the motor had been run with the conrod disconnected it would have smashed it and the cylinder bore to pieces. There are no marks anywhere from flailing conrod etc.
    Cheers,
    Chris


    2014 D4 TDV6
    1954 86" (I'll finish it one day.....)
    1980 Stage 1 v8

  4. #4
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    Question, if piston rings are renewed, is it required to renew the chrome bore liners as well? The workshop manual says the liners cannot be honed. Is there any other method to allow new rings to rebed? Is there a "backyard" fix rather than new liners?
    Chris


    2014 D4 TDV6
    1954 86" (I'll finish it one day.....)
    1980 Stage 1 v8

  5. #5
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    Quote Originally Posted by cjc_td5 View Post
    I am rebuilding a 3.0l 4JH1 engine for a landy conversion. I acquired a non running engine to see if it is rebuildable. It came from a 2004 NKR 200 truck and was described as seized.


    Taking the head off, #3 piston was free and could be removed to reveal the bearing cap missing and a damaged big end bearing. With the bottom end now stripped down, big end bearings #2 & 3 are scored plus at least one main bearing. The missing conrod cap and bolts were in the sump. Apart from scored shells, the conrod, cap, piston, bore and bolts appear undamaged!


    I would expect that if the conrod bolts came out during service then all hell would break loose in terms of crank-conrod contact, or necked bolts etc. There is nothing. A few of the sump bolts were loose, so maybe it was inspected before it catastrophically failed?


    What are the symptoms of multiple bearing failure? Screaming noise? Enough to stop before catastrophic failure?


    So on from here. These cranks appear to be not regrindable. I have a lead on a replacement 2nd hand crank. Obviously new shells required throughout. The manual says the bores should not be rehoned. Should I replace the rings whilst here?


    Another issue may be flushing everything to get rid of the chrome flakes about the place?


    I'd value your advice.


    low oil pressure and spun bearing (effect/cause cause/effect), it was then stripped and left in pieces as uneconomical to repair.

    replacing the rings is a good idea, if you dont want to do the liners you can get ceramic buildup done on pistons to "oversize" them (and its great for cylinder life too) you can give the liners a very light honing but they cant be rebored with any reliability..

    AJAX down the air intake at full biscuts will bed in new rings....
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

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    Archaeopteryx 1990 6x6 dual cab(This things staying)


    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
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  6. #6
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    Quote Originally Posted by Blknight.aus View Post
    low oil pressure and spun bearing (effect/cause cause/effect), it was then stripped and left in pieces as uneconomical to repair.

    replacing the rings is a good idea, if you dont want to do the liners you can get ceramic buildup done on pistons to "oversize" them (and its great for cylinder life too) you can give the liners a very light honing but they cant be rebored with any reliability..

    AJAX down the air intake at full biscuts will bed in new rings....
    Thanks Dave.
    Has a 4DB1 got chrome plated bore liners? When replacing rings, are the liners replaced as well?
    C
    Chris


    2014 D4 TDV6
    1954 86" (I'll finish it one day.....)
    1980 Stage 1 v8

  7. #7
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    rings, not always, pistons, usually.
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    TDI D1(parting/ed)
    Tdi autoManual d1 (Kept it for the girlfriend)
    Archaeopteryx 1990 6x6 dual cab(This things staying)


    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

  8. #8
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    Quote Originally Posted by cjc_td5 View Post
    Thanks Dave.
    Has a 4DB1 got chrome plated bore liners? When replacing rings, are the liners replaced as well?
    C
    I dont recall,

    rings, not always,

    pistons, usually.
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    TDI D1(parting/ed)
    Tdi autoManual d1 (Kept it for the girlfriend)
    Archaeopteryx 1990 6x6 dual cab(This things staying)


    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

  9. #9
    Join Date
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    Bunbury, WA
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    I have sourced a 2nd hand good condition crankshaft and new bearing shells. The Isuzu workshop manual has a process for Plastigauge measurement of bearing clearances, and a specifies max clearance of 0.1mm. I have checked the clearances which measure off in the range from 0.5-0.8mm. There is no minimum clearance specified in the manual. What would be an acceptable MIN main bearing clearance??
    Chris


    2014 D4 TDV6
    1954 86" (I'll finish it one day.....)
    1980 Stage 1 v8

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