I need some clarification on what can cause the number 2 cylinder to have a hole in the cylinder wall, and piston. The reason I ask is because the warranty company that I have my extended coverage with is saying they're not responsible for the repairs because the cylinder "over heated" and there is a clause that states over heated parts aren't covered.

Now I thought the reason for the failure was due to predetonation. Does this sound correct, and if so what will cause this to happen? I'm trying to get all the information I can to battle the adjuster that came out and made the assessment of only 1 cylinder over heating and no other. Oh, I have a 99 XJR with 194,000 miles. Thanks for your time.

 

I would have thought you'd find a broken or bent valve as reason for that kind of damage - Failed upper chain tenisoner let timing chain slip, put valve thru piston, broke valve off and put it thru cylinder wall? Check the tensioner and cam timing for forensic evidence to refute overheating.

 

Engine overheated, intake valve seat dropped out of cylinder head recess, seat fractured, derbis perforated piston crown.

I saw a pair of heads on a 2001 XJ8 drop nearly every intake seat. I have another 2000 engine that only dropped one, but did not fracture. In fact, that's the shortblock that I built up for a poster here who is driving with it in his S type.

 

So engine did overheat? Not sure how, never went into the red, and coolant was full.


Thanks for the timing work around. I'll see what my mechanic says.