Back in November, I went on an epic off-road trip with some friends in their two Nissan Frontiers. I led the way in “Project Slow Devil,” my 1948 Willys CJ-2A, whose engine I flooded in a giant mud pit. While one of the pickups did end up with two dents and a torn front lower fascia, now it’s clear that it was my Willys that took the biggest beating.
“I’m Trying To Save My World War II Jeep Engine After Filling It With A Huge Ice Block,” I wrote just a few weeks after the aquatic episode shown in the photo above. After flooding the engine, I towed the Jeep home and foolishly let it sit a few nights, during which the outside temperature was well below freezing. The water in my engine turned to ice—something that became obvious as soon as I tried removing the dipstick (it wouldn’t budge).
In time, things warmed up, the ice-block in my engine melted, and I drained the motor. I discovered an alarming amount of dihydrogen monoxide in the crankcase, as evidenced by the high pitch of my voice in this video clip:
The good news is that, as soon as I drained the crankcase and refilled it with oil, the engine turned over just fine—well, with the spark plugs out:
Something was preventing the starter from spinning the motor against the cylinders’ compression, but I wasn’t sure what, exactly. I later moved the Jeep into my garage and disassembled, re-greased, and reinstalled the starter. I also charged up a 12-volt battery (the Willys uses a six-volt system, but a 12-volt battery works well with the starter) and hot-wired the starter with the plugs out, spinning it over for about 30 seconds.
That seemed to do the trick, because after threading the spark plugs back in, all it took was a little spritz of starting fluid and the engine fired right up.
But it sounded terrible!:
That noise you hear in the clip above is almost certainly a rod knock, as it has a certain “solid” quality to it, versus a lighter noise you might get from the valvetrain. The horrible clunk also remains prominent when I rev the engine—a telltale rod knock symptom.
What I think happened is dirt from the mud pit I got stuck in ended up wiping my bearings clean—bearings that I had actually replaced just a few years ago. This made it harder for my motor to crank, and once I did get the engine running, there was an enormous chasm between the crankshaft and connecting rods, so now the rods just bounce against the crank as the cylinders fire, yielding the knock.
Long story short: Driving through a deep mud pit, filling your engine with muddy water, and letting that muddy water freeze is likely to ruin your engine. It sure as hell ruined mine.
I haven’t decided what to do with this Jeep. It’s always run and made good power, but the cylinders each make just 80 PSI of compression, indicating that my cylinders are worn. (They should be around 120 when fully healthy.) Had that compression figure been higher, I could have avoided a full rebuild—which would involve boring out the block and installing new pistons/rings—and just removed the crankshaft, had a shop grind its journals down smooth, and then tossed in some new bearings. (I’d also have snagged a new camshaft as well.)
The problem is that I’ve already borked up this cylinder block with some wonky helicoil jobs, so I’m not sure if rebuilding this particular unit is worth all the time and money. My friend Brandon has offered me a free motor, so I may just go that route, but the VIN for this vehicle is on the engine, so I’ll have to figure that out, too.
My plan after the Nissan Frontier off-road trip was to actually sell the Willys, so this is a bit of a setback on that front. But hey, it’s just a reminder that dumbassery has consequences.
Luckily, I’m willing to wrench, so I have the luxury of letting my dumbass flag fly sky high pretty much all the time.