DustyDee

This isn't my picture, but it's pretty much the same. The oil pump is on the crank shaft. Valve seals will be replaced. New gaskets for everything that came off.

I finally got the cam shaft out last week. That is a bugger of a job right there. I had to drop down the steering assembly and front differential in order to get the oil pan off, so that I could remove the bolt from the oil pick-up tube on the bottom of the oil pump, so that I could remove the oil pump, so that I could get the timing chain off, so that I could get the cam shaft out.... did you follow all that? I sent the cam shaft off to get re-done. The one lobe was damaged pretty good. I should be getting it back any day now. Then I get the fun job of putting it all back together! I'm hoping to have it done this week. While I got it apart I'll be cleaning up the heads and re-seating the valves. What else should I do while I have it all apart?

Looks like the plastic lifter holder failed. It allowed the lifter to spin sideways so it was no longer rolling on the cam shaft. Cam is damaged and will need to be replaced also. This just keeps getting better... Time to pull the radiator off.

Thanks. I fully understand that diagnosing engine problems solely based on information from an internet forum is not the best way to do things. I should probably just take it to the shop and get it fixed there, but I enjoy the challenge too much. Well, time to tear it down again. Wish me luck...

Thanks for the info! If I'm reading the repair manual correctly, that means I need to take the head off again to get to the lifters... new head bolts, new gasket, more $$. Crap, why didn't I think of this earlier. Anything else to check before I take the head off again? Edit: when I had the valve cover off last time, I cycled the engine through a few rotations using a wrench on the crank shaft; the valves on that cylinder lifted and closed like they are supposed to. What deactivates the lifters? Maybe that is where the problem lies.

Compression on cylinder #4 is 100 PSI, the other cylinders varied from 105 PSI to 120 PSI. I did not inspect the valve lifters or the cam lobes when I had it all apart. I am kicking myself for not doing that... I am pretty sure that it is not an Atkinson engine. It is the LFA engine code: 6.0L, V8, sequential fuel injection. That's a video clip that I took to show the noise that the engine is making. Hopefully the sound comes through okay. Thanks, Dusty

Nope. I swapped the #4 wire with #2, and the code did not follow. I'm working on swapping the coil packs to see if that makes a difference. Should be able to get that done tomorrow. All the Hybrid gear in there makes it tight to take the coil pack off the passenger side.....

I have an inline spark tester. It lights up like it is supposed to. I don't see the reason for changing wires and coil packs.

I need some help! I have a 2009 Chevy Hybrid, 6.0L V8 engine, about 150,000 KM on it. While driving home, the whole vehicle started to shake violently, and the engine light came on (flashing). I checked the code and it is a P0304 cylinder 4 misfire. I drove it home to the garage and have been troubleshooting the problem since then. I am stumped. I have changed the spark plugs, all of them. I have confirmed spark using an inline light style of tester. I checked compression and didn't have any on that cylinder, all the rest were normal. I pulled off the head and cleaned up the valves and valve seats. Cyl 4 was pretty dirty with lots of excess carbon build up. I took the head to the machine shop to resurface it. New gaskets all around; everything back together. I now have good compression on that cylinder. But I still get the misfire code and the engine shakes. I checked the signal to the fuel injector with a noid light and I get proper signal. I replaced the fuel injector. I took it for a run that evening and the code didn't show up, but the engine still shook. The next day the misfire code showed up again. When the engine shakes, it shakes the entire truck. When it first happened I thought I threw a wheel weight. The shaking is most prevalent when at low RPM, with a low load. When I get the RPM's up there, it is still slightly noticeable, but not as significant. When I have the truck in park or neutral, it still shakes. When I am coasting down a hill, it doesn't shake, and often the flashing MIL will go away. The shaking is the worst when I am slowly pulling into the garage, or other parking spot. Any brilliant ideas on what to look at next? Thanks, Dusty