Originally Posted by Hangwire
Regardless of the symptoms there is no reason to immediately assume engine destruction. Faulty ignition components are some of the most common issues and will cause these motors to run like *** and sound horrible. The failure that you have run across in your motor is one in a million and very bizarre.
Faulty factory cam hardware installation and/or faulty service done on the heads down the road caused this chain reaction. Its too bad but at least once you are done the thing is fresh and will last a very very long time if properly serviced.
If you immediately tore down every engine with bad noises without changing or inspecting anything I have a feeling youd waste quite a bit of money over a life time. But maybe thats the crazy in me.
My point was, I know what a mechanical problem sounds like, especially when using a stethoscope to pinpoint it combined with codes showing misfire in the same location. Nor did I tear down the engine without doing an inspection. I pulled codes, listened with a stethoscope, swapped plugs and coils, and finally did an oil pressure and compression test before tearing it apart. That's a rather complete diagnostic. After listening to the engine run, there was no doubt in my mind that it was a mechanical problem on the top with #3 and #4, and I was exactly correct.
I can't imagine this was a factory defect and the engine "survived" 143K miles. It would have self-destructed long before this. Someone was in this engine and didn't bother to torque the cam bolts properly. We are ordering new heads, fully assembled. I am for sure going to check the torque on the cam bolts. I will probably remove the cams and make sure there is plenty of assembly lube and then reinstall and torque them to factory specs. I actually think the rockers fell out as we were removing the valve cover. We heard some strange noises from under the cover as my son was removing the bolts around #3 and #4 on the cover.