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1991 grand wagoneer 5.3 motor only swap

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  • 1991 grand wagoneer 5.3 motor only swap

    I had been contemplating on what to do with my grand wagoneer for a couple years. Back story is my grandfather bought it used in 1993 and drove it til the day he died(almost literally). My grandmother drove it during the Idaho winters for another 10 years or so before she ended up in a nursing home. I bought it from her and got a one way plane ticket to Idaho and drove it home to Oregon. I've had it for 4 years now. Total miles on the clock 136000.

    Everything on it was original and everything works except the overhead compass/temp display. I drove it every once in awhile as I had other vehicles. This last year we paired the fleet down to one family vehicle and the jeep(much to my wife's displeasure, shes not a fan of the jeep). Being that it's a "rare" 91 final edition I wrestled with keeping it stock or modifying it. I finally got tired of being eye to eye with Subaru owners at stop lights and lifted it 4" and put 31's on it.

    Now the original 360 ran ok but was gutless with 31s(stock 3.31 factory gearing) and was showing it's age. It leaked oil from every seal, the carb needed rebuilt, the alternator was starting to intermittently not work, and the starter was in the same boat. The nail in the coffin was it vapor locking on me during a 90+ degree summer day while going over the cascade mountains for a camping trip. So I started planning.....

    I wrestled with rebuilding the 360 and putting the Edelbrock pro flow efi system in it. Approx cost was estimated around 5500$ depending on what all the engine needed during the rebuild. My issue is I'd still be stuck with a turd of a motor that used cork gaskets for everything....not ideal. So I looked into what a 5.3 ls swap would cost. I didn't want to do the entire drivetrain swap like everyone else does as my trans and tcase work fine. Also wasn't fond of trying to make a 3spd column shift work with an od trans and the other ways I've seen tcase levers done. I don't really care about mpg as I don't drive it every day. So I researched as much as I could. Called a few vendors and they thought I was nuts! I saw forum member on another site post about doing the same swap successfully so I pulled the trigger and collected parts. I kept a running sheet of cost totals and marked a date on the calendar to start with the hope of having it running quickly.

    The day came and a buddy and I tore into it. I'm an ex Chrysler master tech and my buddy is a diesel tech. We didn't pull the fenders or front core support like everyone else does. Just the hood and did the whole thing in my garage. Had the old engine out and the junk yard sourced 5.3 from an 01 Tahoe bolted in a day and a half. I used flying iron fab motor mounts and the advanced adapters transmission adapter and it all slid right in without any issues. I worked on the actual hard stuff for about 6-8 hours a day for a week. I put a 97 blazer 2 door tank and pump in the back and deleted the oe saddle tank. Ran -6 an ptfe fuel lines, made a custom fuel fill adapter as jeep hoses are 1" and the blazer tank was 2", had a custom ps pressure line made, had to figure out custom radiator hoses as I reused the original jeep radiator. The jeep mechanical fan bolted up to the Chevy mechanical fan clutch after resizing the holes. I used the harness and pcm that came with the engine and wired in the required relay/fuse panel. Had flash the pcm, also their website was a godsend of info for the wiring. Used the original 5.3 exhaust manifolds and we made a custom down pipe that hooked up to the oe jeep cat and muffler using prices of the jeep and Chevy down pipes. Installed adapters on the engine to run the jeep oil psi and coolant guages using the oe jeep senders. There's more I'm sure I'm forgetting feel free to ask.

    In total it took 1 full week and another week of working a couple ours a night on it......and it runs and drives! Holy crap what a difference! Power whenever you need it! It does burnouts now! I can get in and start it up dead cold and without hiccups! I've put 40 miles on it so far and am taking it for a couple hundred mile trip over to eastern Oregon for some much needed dirt bike therapy this weekend so we will see how she does. I'll report back. Also, total cost including the engine...4000$ not too bad(even includes having the rear driveshaft lengthened/rebuilt). I'll post pics once I figure out how to do it. Let me know if you have any questions!
    Last edited by Jeepfamily; 03-10-2022, 09:20 PM.

  • #2
    Just got back from my trip. 240 miles round trip. Towing a 2400# trailer with 500 pounds of guys and gear from 500 feet to 5000 feet to 3000 feet and back. 11mpg. I was impressed. Only had to kick it down to 2nd for the steepest grades. Much improved over the old 360!


    • #3
      That's awesome! What a great story and logical thought process. Another FSJ on the road for a long time!
      Chuck McTruck 71 J4000
      (Chuck McTruck Build Thread)
      79 Cherokee Chief (SOLD, goodbye old buddy)
      (Cherokee Build Thread)
      11 Nissan Pathfinder Silver Edition 4x4
      09 Mazdaspeed3 Grand Touring
      00 Baby Cherokee


      • #4
        Update. Been driving it around a fair bit. Did a drive yesterday. Mostly highway 55-60 mph going from 500ft to 1500ft with about 300lb of gear in the back. Round trip I got 16.4 mpg. Not too shabby!