Well, after some prompting from JohnnyC, I'm going to post my series of unfortunate events. Hopefully the lot of you get a kick out of it.
To begin: some backstory. I have a '94 Grand Cherokee with the 5.2L, which came saddled from the factory with the (kinda crap) Seimens Deka single-pintle fuel injectors. Looking for a cheap upgrade in performance/mileage, I grabbed a set of Bosch 4 injectors from the junkyard and rebuilt/flow tested them. With all the injectors looking good, I finally got around to installing them a few weeks ago. Installation procedure is as follows:
Remove all throttle linkages
Remove throttle body
Remove fuel rails with attached injectors
Install new stuff and bolt back together
Fairly straightforward stuff, but I'd forgotten to pick up a TB gasket the day before so I had to get Cambodian Tire to order one in for the next day, no big deal. Reinstalled everything but the throttle body, no worries. I places the TB back on top of the intake to keep crap out of the hole.
The next afternoon I grab the gasket, get everything torqued down and go to fire her up. She runs rough for about 3 seconds and then goes klunk KLUNK HRRRRNGH. Fearing the worst, I hit the starter again, and the starter engages but can't turn the engine over. She's seized solid.
Now, at this point I'm totally baffled as to what just happened. I haven't touched the internals, and while the engine has a tone of miles on it, it would be one hell of a coincidence to just randomly eat itself just after doing some work on the engine. Over the long weekend, I pulled apart as much of it as I could in my condo parking lot, thinking maybe the timing chain had snapped and bound up in the case, because even with a 18" breaker bar on the crank being leg-pressed with no spark plugs in it, this engine wasn't turning a millimeter. Timing chain was old and sloppy but otherwise fine. Likewise, removing the valve covers showed all valves accounted for. No undue metal in the oil. Pulled the starter, it's fine and not jammed. All accessories removed. Eventually pulled the oil pan with the motor still in the vehicle, nothing appeared wrong with the bottom end. I was stumped.
Fed up with working in a parking lot and knowing I'd have to give up and pull the power(less)plant, we loaded it up on the trailer and hauled the Jeep out to my dad's garage so I could borrow his space and engine hoist. The rest of the story, I suppose, is best told with pictures.
In the garage, finally. Pulled the hood for engine access.
This is how far I'd stripped it down in my parking lot, but bad weather all week had kept me from going any further.
Personally, I wanted to just do an engine swap, but I determined that the headers wouldn't fit. Oh, well!
Many linkages were unbolted and wires unplugged, and the engine is almost ready to be yanked.
Out, finally!
Required.
Got the motor on the engine stand, started removing all the bits and pieces. Everything looked normal, until....
....I pulled the passenger-side head. Gee, that piston looks pretty cracked. Wait, what is
that?
WTF WHY IS THERE A TORX BIT IN MY COMBUSTION CHAMBER. YOU ARE A TORX BIT, YOU DON'T EVEN BELONG THERE.
So, at this point it became suddenly apparent what had happened. Way back last year when I first bought the Jeep, the very first thing I ever did with it was clean the IAC valve on the back of the throttle body as the idle was a bit odd. The ISC is in a very awkward position with little clearance, so I was forced to use a removable screwdriver bit in a ratchet to get at the two Torx bolts holding it to the back of the TB. While I was reassembling it, I dropped the bit down the back of the engine. I searched for that frickin' thing for HOURS. Magnets, flashlight, I couldn't find it for the life of me. Every time I went under the hood to work on something, I looked for that damned bit. eventually I was forced to assume it had fallen out of the engine bay while I was driving.
Flash forward to a few weeks ago. After lots of driving and many bumpy Waiparous trips, the Torx bit must have somehow migrated forward to the front passenger side injector pair and was in a position near the injector hole for that cylinder. Keep in mind that the ECU wiring, fuel rail, and a vacuum line cluster all run down that area. As soon as I pulled the rail with injectors attached, the bit must have been in the perfect position and jumped in the hole. Here's a picture showing in red where the Torx bolt I was working on was when I lost it, and in green the hole it went in over a year later.
Also note that the hole has a raised lip around it to help protect against exactly this kind of thing. I afterward attempted to find a position it could have rested in on the intake manifold to drop in, and after a number of trials I was completely unable to make the bit fall in the hole. It barely fits in end-on. The chances of the series of events conspiring to have this happen was infinitesimally small... and yet there's a sodding Torx bit in my piston.
So, yeah, that's the story more or less. The transmission also seems to have degraded badly in the months since I swapped transfer cases, as it gushed some pretty badly burnt ATF when I pulled the TC, indicating that it's blown an internal seal and something was badly overheating itself. The culprit may have been a clogged checkvalve by the trans cooler, which would have kept the ATF from circulating and cooling properly. Thus, I will be having the trans rebuilt and beefed up a bit. Also looking to snag a 5.9L but if I can't track one down I'll just rebuild the 5.2.
Bonus image: The piston needed to be bashed out with a hammer to unseize thing so I could pull the rest of the internals on Sunday. Hulk smash!
So there you have it. Have I mentioned I hate Torx?
Topic: Torx and Jeeps - A Cautionary Tale. (Read 5211 times)