I stand looking at the 4.0-liter engine I’ve just spent hours installing, sweat and grease dripping from my face. After sitting for nearly a year, now has a new engine, and it’s all hooked up. But I’m not happy, because on the crankshaft damper sits a breaker bar that will not budge. The motor is seized. I am defeated.

This time, I really screwed up. Badly.

Nearly a year ago, I bravely (and naively) took on a powerful, evil foe: a deep mud pit in a Michigan off-road park. But despite our valiant fight, my Jeep and I wound up shattered and defeated, the Cherokee leaving with a hole in its oil pan, and me leaving with a hole in my heart.

But after weeping myself to sleep over the loss of my very first engine, I brought myself back to health after training with the rigorous software called “Craigslist.” In time, I grew strong again, finding a cheap $120 engine to replace my old one, which, I had discovered, .

I purchased the dirt-cheap engine from some wild and in the woods of rural Michigan, and returned it to my lair. But the powerplant sat for nearly a year before the I could muster the strength to even look at the Jeep’s rusting, powerless body.

In time, though, I began the project, freshening the engine up in a quest to breath new life into my first automotive love. I replaced seals, pumps, lifters and the timing chain, and after a few weeks of wrenching, the engine and I were both ready to resuscitate the Jeep.

So I hooked up a crane and dropped the heart into the XJ’s open chest. Then came a truly beautiful moment: the four-liter engine “popped” right into the transmission’s bell housing and immediately, the shining sun replaced clouds, and my world changed from dark and gray to one filled with color, beautiful sounds and rich aromas.

Still, I had much work to do, so I spent many hours wrenching into the night, bolting the engine to the transmission, hooking up all the electrical connections, affixing the starter motor, bolting on the accessory drive, and hooking up the exhaust.

The final step in the transplant involved fastening the engine’s flex plate to the torque converter. To do this, I had to rotate the engine by hand to line up the bolt holes. I grabbed a small ratchet, popped it on the crankshaft balancer, and gave it a spin.

Nothing.

So I grabbed a breaker bar and put it on the balancer, figuring it should only take a small push with that bigger lever arm.

Nothing moved.

My eyes grew wide, rain began pouring and the colorful world turned to grayscale when I realized: the engine was stuck.

I fell to my knees, looked up at the gloomy sky and yelled and cursed to the car gods above. All of those hours spent getting the engine, freshening it up and installing it—all for nothing.

I regressed into a state of wrenching depression, unable to stand the sight of a ratchet or the smell of PB Blaster. Craigslist postings of pristine, rust-free Jeep Comanches no longer stirred my soul. I was lost.

But in time, I realized what I had done, and it was very stupid.

Because the new engine’s rear main bearing cap was covered in hard gunky sealant that could compromise the rear main seal, I had simply taken the rear main bearing cap from my old engine, slapped in the new engine’s journal bearing, and fastened them to the new engine.

I figured the caps were the same between all engines, and that as long I didn’t mix the actual bearings, I’d be fine. But I was wrong, as the rear main bearing now clamps that crankshaft like a drum brake, preventing it from budging even with a 150 pound human hanging off a two-foot breaker bar.

The good news is that this is probably fixable; the bad news is that removing the oil pan with the engine in the vehicle is a bit of a pain in the butt. But alas, I don’t have much of a choice.

I’m off to go do that now, so we can find out if that $120 engine—which sat in a man’s field for months covered only by a can over its throttle body—actually has enough life in it to revive the vehicle that got me into wrenching in the first place.