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Here is the backstory.

Wife had her 2004 Jeep Wrangler running and driving fine and the transmission went out about 2 years ago, it was a 42rle. The Jeep sat at her parents ranch outside with no transmission in it. She recently bought a used transmission (42rle).

I installed it myself and got ready to bolt it up to the flywheel when I noticed the engine wouldn't turn by hand. I tried turning the engine over with the key, and it did one rotation and wouldn't budge after that, neither by the starter nor by hand.

Furthermore, I squirted liquid wrench down the spark plug holes and tried turning it by hand again, and it wouldn't budge. I now have the heads off, starter off, oil pan off, and still cannot get the engine unseized. I have tried taking a butane torch to heat up the cylinder walls/pistons, and banging the pistons with a hammer and wood block, then a hammer and steel pipe, no luck. The front damper bolt won't turn the engine, that's what I've been trying to turn it by hand with a breaker bar and a cheater bar that is about 3.5-4 feet long, it has been turning the bolt eating at the washer and not turning the engine.

Any advice as to get this thing running again? I feel like I'm running out of options, and I'm going to have to go buy her a new engine...

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  • Welcome to Motor Vehicle Maintenance & Repair! May 25 at 23:35
  • Banging on the pistons won't do anything useful unless you first remove the crankshaft, because trying to push one piston down is also trying to push other pistons up and wedging them even tighter. (And using a "hammer and steel pipe" has probably done unrepairable damage to the pistons even of you did free up the engine. A cracked piston disintegrating while the engine is running is not fun!
    – alephzero
    May 26 at 19:02
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More than likely when the engine sat for so long, one or two of the cylinders (open to the elements via an open intake or exhaust valve) became rusted. When you turned it over, it forced the piston rings up into the rusted area of the cylinder and now it is stuck.

You have two options, depending on your pocket book.

  1. Take what's left of the engine out and take it apart. When everything is apart, you'd need to re-hone the cylinders and then reassemble everything. If you go this route, you should get a rebuild kit with rings and bearings and do it right. This will take more work than option 2, but will be by far the most cost effective means of getting things done.

  2. Find a used engine and purchase it. This is by far the easiest and quickest way to get things done. There are plenty of 4.0L I6 engines out there. They really aren't that expensive. Finding one which has low miles and in good shape might be a bit of a trick, but shouldn't prove too difficult.

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