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Thread: 4.0 Main and Rod Bearing Replacement

  1. #1

    Default 4.0 Main and Rod Bearing Replacement

    Hello everyone,
    Its nice to be in the presence of professional.
    I need some advice on the following; I am getting ready to replace the connecting rod bearings and main bearings in my fuel injected '98 cherokee 4.0. I completely rebuilt my chevy 350 not to long ago but that was with the engine on the engine stand. I'll be doing this job with the engine in the jeep and me on my back. I have already replace the oil pump and timing chain a few months ago.
    Question; Can I get away with just loosening up the main caps to very gently removing the old bearings that are towards the motor be pushing the bearing out from the side opposite the notch in the bearing?
    Question; Do I have to remove the timing chain?
    Question; I am only replacing main and rod bearings, do I have to prime the motor?
    Any advice, ideas, critisicms, are appreciated.

    Thanks,
    Robert D.
    "Do the work yourself and keep the money in your pocket"

  2. #2
    Registered
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    Default

    Was it knocking? Why change these? Do you know for certain what has been done to this engine before? (IE shaft turned in previous rebuild) IMHO I would NOT change the bearings without turning the shaft, which would mean it needs to come out! Can it be done, sure,,, its your money and your time on the side of the road/trail! I have seen (my Dad) cut tin cans and make shims to go behind the bearings, it worked and worked well enuf the car ran for several years! (without knocking)

    Good luck, gravity is going to be against you,,,,

  3. #3
    Registered ryan86jeep's Avatar
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    Default

    i did the rod bearings with the engine in
    jeep on the lift

    it was super easy on the 4.slow
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  4. #4
    Stroker Fever Dino Savva's Avatar
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    Quote Originally Posted by rjdnrd1 View Post
    Question; Can I get away with just loosening up the main caps to very gently removing the old bearings that are towards the motor be pushing the bearing out from the side opposite the notch in the bearing? Yes.
    Question; Do I have to remove the timing chain? No.
    Question; I am only replacing main and rod bearings, do I have to prime the motor? Just coat the bearings in engine oil when you insert them and before you fire up the engine, pull the coil wire off the distributor and crank the engine first to get some oil pressure going.
    Any advice, ideas, critisicms, are appreciated.Get the Jeep as high off the ground as possible if you're going to do the work lying on your back (drive-up ramps are very useful here), and wear safety goggles to keep oil and dirt from falling into your eyes.
    Have fun.

    1992 XJ 4.6L "Poor Man's" Stroker
    202rwhp @ 4700rpm (248bhp)
    258rwtq @ 3400rpm (311lbft)
    1/4 mile: 14.63 @ 94.4, 3450lb curb
    AX15, NP231, D30/D35
    Jeep Performance, Jeep Tech, Junker to Stroker

  5. #5
    Registered TheLoneRanger's Avatar
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    Exclamation

    Inspect the old bearings closely for any markings;
    if the crank's been turned before, the bearings will
    have markings (such as .010 undersize).

    I'll also question the reasons for this job; is it knocking,
    or does it have very low oil pressure?
    96 XJ 2-dr Sport, 4.0L, AW-4, ChryCo 8.25, Ecco alloys with BFG L/T's, 3-row CSF rad, Forest Green.....

  6. #6

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    Have some questions with the same issue:
    How can I lose bearing 4? It has no oil hole, so I can not take the braring out.
    Any ideas?
    Thanks
    Avigdor

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