Hi
I had the same problem on my 04 se7 and the misfire was on cylinders 4 and 5. Those plugs were actually wet with oil. The top center head bolts were loose due to the threads coming out and the head gasket burned up to the valley area. Replaced the bolt threads with ez lok threads and am still in the process of putting it back together, but I believe that was the problem since they're was no mixing of oil and coolant. Just some food for thought. Every disco is different. This was the first I had heard of my problem.

 

Had a few minutes tonight to pull some plugs and take a look with my borescope. Plugs look pretty good except #5 of course which was oil soaked. The rest had some slight carbon. Running platnium 4+ for about 12k now. No cylinders looked steam cleaned. All the pistons had some pretty good carbon build up with a slight oily appearance.

 

That really sounds like a leak from the head gasket to the valley. If it is you should be sure to at least tap the head bolt holes by the leak, but most likely you'll need a new sleeve in those holes. I used ez-lok from fasten all and they blew the heli coils away. I stacked up 1.5 of them, but I think one would do the trick.

 

Well its confirmed, blown gasket and a pretty good one at that. At least 3/4" missing. I am also shocked at how clean the engine is for 77k on the clock, that Rotella stuff is no joke. The threads look ok for the bolt between #5 and #8. Heads and block are not warped. I got a valve that looks a little gray so gonna get that taken care of.

 

http://enginecodemaster.com


http://enginecodemaster.com/enginecodemaster/index.html

 

I'm not saying all blown hg's are the same, but that's exactly how mine was and the threads looked fine until I tried to torque the head bolts and the threads by the blown section pulled out. You may want to experiment with putting some torque on that hole between 6 and 8 before you torque up all of your other books and have to buy a new set. It is a real pain in the ***. Maybe use an old head bolt and torque to 70 ft lbs just to be sure you don't have a problem. Good luck.

 

Well then, cylinder #5 has a wet plug, coolant leak only 40lbs pressure...this really sucks.

well 40 psi is double the operating pressure of a normal engine, no dough it would leak.
are you doing both head gaskets or just the one?

 

Both will be done, would be crazy just to do one side. I have the "tick" as noted by numerous others on this forum but I did note that all the liners are in place none are dropped below or proud of the deck and the heads have no ring cut into them so must be something else...

 

Thanks, will keep an eye on that one. Going with TTY bolts as well.

 

i would suggest decking the heads again and using stud, but that just me