After many miles of faithful service, my Jeep was brought to its knees by three engine mount bolts that decided to break off into the block. I had to break out the ol’ cherry picker. Since the engine was out, I decided to tear into it. Come check out the innards of a 250,000 mile engine.
One fateful night, as I drove home from work in my beloved 1992 Jeep Cherokee XJ, something horrible happened. The car started shaking. A loud banging noise rang through the air. I coasted the car into a gas stop. Coolant was leaking everywhere. I popped the hood. It was bad. Real bad.
What caused all the ruckus? Somehow, all three engine mount bolts on my passenger side had sheared into the engine block. That’s kind of a big deal, since the engine mount connects the engine to the car (the two red arrows below show where the engine mount brackets connect to the engine).
In other words, my engine basically broke free of my Jeep and was floppin’ around my engine bay like a fish out of water, destroying everything it its path.
There was carnage. Among casualties were the radiator, fan, and fan shroud. When the bolts broke, the motor shifted forward and rolled over to the passenger side. The fan crashed into my radiator and shroud. The fan itself eventually slammed into my unibody rail, bending each of its blades and finally coming to an abrupt halt.
Worse than any of this, though, was the fact that I now had to somehow extract three bolts that had broken flush with my engine block. Wunderbar, as they say in France, I think.
I tried extracting the bolts with the engine in the car with one of those right-angle drills, but there just wasn’t any space between the unibody rail and the engine, so I decided to give the ol’ motor the yank. A quick trip to Harbor Freight, and I had myself a cherry picker.
I yanked the motor, put it on an engine stand, and started taking stuff apart. With the engine on the stand, I was able to drill nice clean holes right into the broken bolts, and extract them all with an EZ-out tool.
So, problem solved, throw the motor back in and call ‘er day, right? Nope. That’s boring. So I tore into the motor and replaced lots of stuff.
What I found inside surprised me: the engine, after 250,000 miles, was still in excellent shape. A bit of grime here and there, but she looked good. Open up that video above, and I’ll give you a tour of the ol’ 4.0-liter. Or, if watching a video at work will get you canned, read on.
What I Learned From It All
The Jeep 4 liter is the greatest engine ever built. It has all the low end torques, and they should never have stopped building it. OlllllllO. Okay, so, now that I’ve got all the Jeep fanboys’ attention, I’ll talk about the experience of pulling and refreshing the engine.
You folks have read about my wrenching escapades before. Yeah, I seized an engine by soaking the cylinders in starter fluid. Clearly, I’m not exactly a genius when it comes to wrenchin’, so when it came time to do a huge job like pulling an engine, I was a bit nervous. How would I manage to screw this one up?
It was the first time I’d ever taken an engine out of a car. It took forever. I had to remove the cooling module, the front fascia, all the electrical and cooling lines, the air intake, the flux capacitor, the exhaust, the throttle linkage, and tons of other stuff. Actually unbolting the engine from the car was rough. The bolts were a pain in the butt to get to, and required all sorts of odd contortions and special tools.
Thank goodness I had a friend who was labeling all my bolts and parts for me, because I’m not nearly that organized. I’d have just put the bolts down, and “figured it out later.” That wouldn’t have worked out so hot.
Then, once the engine was on the stand, I started going through it. I removed the valve cover, exposing the rocker arms and valve springs (those things next to me in that picture above). It all looked swell, aside from a bit of grime here and there. I took off the exhaust manifold (which had a big crack) and replaced it, as I didn’t want to die of carbon monoxide poisoning. There was some carbon buildup in the exhaust and inlet ports since I had been burning oil for thousands of miles, but it was nothin’ too concerning.
On the bottom end, I pulled the oil pan to have a gander at the crankshaft and camshaft. The oil pan had no metal shavings: just a bit of dirt. The cam lobes looked to be in good shape, aside from a bit of discoloration. Not bad for 250 large on the clock.
I replaced the water pump, timing chain, harmonic balancer, and lots of other parts. It was all pretty straightforward, which is odd, because as a youngster, I always thought these kinds of jobs would be impossible. But actually doing it wasn’t all that bad. Invite some friends over, and just wrench. It was actually fun. And seeing the innards of my old Jeep, and knowing that she still has some life in her: that was just awesome.
Geeking Out is former Fiat Chrysler engineer and current Jalop scribe David Tracy’s weekly missive on all things intensely technical about cars. He can be reached at firstname.lastname@example.org.