Caterpillar C12, and no codes.
Last month I had it on the dyno at Pittsburgh Power, and they think it's getting combustion pressure into the fuel system, aerating the fuel as it goes into the injectors. The guy who checked it out admitted that he wasn't real familiar with C12's, but for the most part, no one is. It's just not a very popular engine. He thought it could be bad injector o-rings or a cracked head. There was also an intermittent issue with cylinder number 4 not firing a couple times after a real hard pull on the dyno. I pulled it apart and replaced all the injector o-rings. The bottom o-rings were completely missing. I also replaced the injector cups because I had a slight oily sheen floating on top of the antifreeze in the overflow tank. I also installed a reman injector in cylinder 4. After it was back together, it had a miss that it didn't have before, which turned out to be the reman injector. Don't know if it's defective or if it'd just that the calibration is so different from the one it replaced, that it's not flowing right. I don't have any way to set the injector calibration. I decided to reinstall the old injector and just give it a try, and the result was no good.
Before I left, I ordered a cheap, mystery injector off ebay. The seller thinks it's a reman, but said it may also be used. I figured I could risk $75 and give that a try. I'll pop that one in on the weekend and see how it runs. If that's no good, I'll have to put the original reman in and see what happens. I'm also tempted to eliminate the primer pump, just to cover that base, though that would be more likely to be a problem in colder temps with the engine loosing it's prime while sitting.
The problem I'm having is that once the engine reaches a certain stress level, it will stutter real bad every time you get off the pedal and then back on it again, or basically when you shift. It would go up a 20 mile long hill no problem if you could stay in one gear, but one you have to shift, the engine is shaking and stuttering when you get back into the pedal. Of course it's down to about 1/4 power when it's acting up too, which is why it's such a big deal. The problem is also ambient temperature sensitive. The hotter it is outside, the worse it acts up, even though the actual engine temp doesn't seem to correlate with the issue. I was just down in Alabama, where it was quite hot, and two new problems cropped up. Popping out of the exhaust at idle and a real rough idle. During this, the engine doesn't sound right. Just has a different tone to it that's not normal.
If I was staying in trucking, I'd just go out and buy a newer truck, as they're pretty much giving them away right now. Things are just complicated by the fact that I am only trying to run this thing for another month, so I'm really limited as to how much money and time I can spend trying to figure it out. I'm not going to get rid of the truck, since I'm in so deep on it I'd take a huge hit selling it. It's a pretty rare truck, so I'm keeping it as a future "collectible". It'll be eligible for antique tags in another five years. It would be nice to fix it, but if it's a major item like a cracked head, it's going to have to wait till some day in the future.
Jeff
) but I knew what it really was.
