Spark plug looks like piston moved too far, smashing it (engine was knocking). I am going to remove the head. Any ideas what happened? Any Jag engine guys here?

 

All bad things. A spun main bearing that has chewed your crank to bits, or the wrist pin has eaten the piston.

Even then, getting to the spark plug is not easy. If it is a definite mechanical knocking sound, you might be looking at a broken valve?

 

Sounds like you'll be pulling the head no matter what, and then the source should be quite evident. If it hasn't jumped time? I would suspect a broke valve. Just a couple quick thoughts .

Jack

 

Or a dropped valve seat if the engine overheated.

 

One thing that can smash the plug is the piston, it is possible that the piston has come apart at the ring lands and the top of it is loose in the bore. I have not heard of that happening on this car, but anything is possible.

 

After thinking on it, the most likely event was skipped timing, piston hits valve head and breaks it off, valve head beats the plug to death.

 

Hopefully, the cylinder will not need a sleeve. I am not worried about crank, I fix them all the time, no big deal. I just drop oil pan and fix conn. rod journal.
Not a sleeve, not a sleeve.... I hate removing engines!!! I was repairing Toyota Sequoja, I removed engine 3 times!!!!!!!
Maybe I should go to church and pray "not a sleeve job!!!"
Wish me luck!!!
It is always a question how smart previous owner was. Morons keep driving cars with knocking engines until they get block hole! Welders charged me $120 to weld a block hole in some Mazda..

 

Hopefully you won't need to work on the crank. I have read where the engine needs to come out if you need to get to the rods due to the "bedplate" on the bottom end. It will be interesting to see what the cause is.

 

I just noticed, spark plug electrode has a print of valve. Most likely valve broke and valve head is jumping inside sometimes preventing engine start.
I paid very low price for the car

 

Cheap car + neglected maintenance = money pit

Do let us know what you find when the head gets pulled!

 

correction:
expensive car bought for low price+repairs=drive, have fun/ sell/ good profit.
5k profit sounds good to me.

 

And I hope it works out exactly like you say!

 

Good Luck!

 

 

No guts, no glory! Hopefully the engine can be fixed at a reasonable cost. I'll be following this thread. Best of luck!

 

I personally dropped a small nut in some engine. Lucky me, I could fish it out with a camera and a magnet. Maybe, I'll use camera for this one, Who knows, there is always a chance for easy solution. I have bunch of car projects and not sure when I will get to this one. I am not done with X-type yet, have to replace washer pump and fix rear bumper cover. Whenever I get to XK8, I'll keep you posted.

 

It's a short list of things that can contact a spark plug. The piston is most likely. Now the question, why? If someone installed the wrong (too long) spark plug, that might do it. A dropped valve?, depending on the orientation of the valve and spark plug. I don't know enough about this engine to say. Since the spark plug is already out, do a compression check on that cylinder. If a valve is dropped, you will have no compression. Compare the compression to other cylinders to see if it's good. If you have good compression, it's probably in the bottom end as was mentioned. Good luck and please keep us posted.

 

car5car,

If you don't have a borescope/endoscope, there are a lot of very inexpensive ones available on eBay that will connect to your phone. That would give you an indication of the condition of the piston and possibly the presence of a broken valve prior to pulling the head.

Sorry you're having to deal with this, but will look forward to your next update.

Cheers,

Don