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Engine swap 1990 YJ 4.2 to 1989 Cherokee 4.0


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  • Engine swap 1990 YJ 4.2 to 1989 Cherokee 4.0

    Is this possible...
    Engine swap 1990 YJ 4.2 litre carburator to 1989 Cherokee 4.0 litre throttle body. The 1989 Cherokee 4.0 litre throttle body engine is used but runs smooth. I am fimiliar that I require to change all the harness and computer.....but...

    Does the housing bolting pattern fit for the tranny and any other possible problems may occur ?
    Will I encounter electrical issues ?
    Someone mechanically inclined indicated that I should purchase a 1991 4.0 litre throttle body instead which no electrical issues will occur ?
    I would rather find out if this is possible cause I am purchasing the 4.0 litre throttle body engine at a reasonable price.

    Please advise
    or send me a email

    thanks in advance.
    Last edited by 1990 jeep YJ; 08-22-05, 02:48 PM.

  • #2
    check your local smog law, in Ca you can't install an older motor into a newer vehicle easily,even if it's "cleaner" you may find that it's still the same engine model...

    as for the bellhousing i think they're the same have a look at this
    Mighty 4 banger YJ, 35's,4.88's, 30 splines, Detroits, 4.5" lift, TJ flares, Scorpion Offroad stuff, blah, blah, blah.


    • #3
      Thank you

      Just wanted to say "thanks for the info". It helped very much.

      I will let you know "How things go" since I bought the engine and its ready to swap.

      1990 jeep yj


      • #4
        I have a 1990 4.0 in my 1980 CJ7, but I used the transmission as well. The problem is the crank position sensor (CPS). On the RENIX fuel injection that is on the 4.0 the CPS is mounted in the bell housing and uses a special flywheel. HESCO I understand makes a relocation kit for the RENIX that moves the CPS to the front with a special vibration damper.

        Take all the wiring, and the computer. That computer is not water proof so put it inside.

        Check the smog laws before you start. Canada?

        1956 Willys Wagon restomod