Hi everyone, this is my first time posting here and I am looking forward to making some new buddies here as I have for the last few years on a Jaguar forum!
Well, my wife got home one evening last week to tell me that our 98 5.2 slt 4x4 was "feeling funny" and the check engine light was on! Whatever happened to "Hi honey I'm home"?lol
I plugged in my scan tool and discovered that #8 cylinder was misfiring, upon removing the spark plug I found that the outer electrode had completely burnt off, I think this may be due to the crappy gas we get here in California's Central Valley, my Jag has had a pinging problem ever since I brought it with me when I moved here from England five years ago! Anyway, I digress, I fitted new plugs to her and yes, she is still missing! I then checked the compression and to my horror got a reading of 90psi on #8 cylinder. I then had a look inside the cylinder with my borescope and could only really see some light pitting to the piston top, I was unable to see enough of the valves to tell if there is any damage to them.
I am kind of hoping that this problem is being caused by the burnt off piece of spark plug preventing the exhaust valve from closing completely, I will be tearing into the motor tomorrow, Sunday, and I will let you know what I find!
I was basically wondering if any of you have experienced any similar problems? My wife has owned this car from new and it has been absolutely no trouble whatsoever, apart from needing a new water pump at around the ninety thousand mile mark, it now has covered just over 160k miles!

 

Well, went ahead and pulled the cylinder head today..... and, hey presto... found a piece of spark plug debris embedded in the exhaust valve seat!
I will go ahead and have a new seat fitted then replace the valve also... just incase! Also at this mileage, and as of tomorrow, having a full set of gaskets, I may as well remove the left head and reseat all of those valves as well!

 

Better have both heads gone through at the shop. You probably have cracked exhaust seats.

 

Hi, yes, I went ahead and gave both heads to my local shop who do all of my engineering work, they cleaned and tested them and, after fitting the one new exhaust valve seat, gave them a clean bill of health!
It will probably be a few days before I can get it back together, we have just got busy.... and paying jobs come first! lol
But thank you for your suggestion, I will post with the outcome!