XJ6 Engine Problem

[Jose]

Thanks Nigel, now I can use the info in the XJ6 forum.

[NigelW]

I've finally found some time to get back to the XJ engine problem that was not sorted out with the stake down kit last year. To this end I decided to pull the engine out , this was done yesterday afternoon. I'll now strip the thing down and investigate further. You never know I might find something that affects S Type engines - I'll let you know.

[NigelW]

Took the cylinder head off today and found #6 combustion chamber in a bit of a mess. Looks like a ring has let go as I dug out a very small piece from the head. I'll take out the piston tomorrow.

[cass3958]

Ouch! How far did you drive it in that state Nigel?

[NigelW]

Not far fortunately as I took it off the road as soon as I heard something strange. What narks me is that it is a genuine jaguar factory replacement engine with only 35k miles on it - all done by myself and with regular servicing.

[NigelW]

Ok so took out #6 piston. No damage to the rings, lands or skirt also no damage the the bore. My only conclusion is the small piece of steel I removed from the piston came from the cylinder head. When I clear up the unholy mess that is my garage floor I'll pull that apart.

[Orlando St.R]

Really sorry to see that, Nigel. How disappointing, especially when the rest of it looks in such good condition.

Hope you manage to trace the cause soon.

What will you be able to do about the damage to the head? I guess you can replace just that piston.

[cass3958]

That looks like an 8:1 ration piston you have there Nigel which means because you have a Hemi head on the XK engine you should be able to skim the head quite a bit and still have room for the piston. Failing that put it back together and sell it.lol.

[NigelW]

I'm putting the dam thing back, I've gone over it with needle files and it has come up quite well, going to do the same with the head as I've had enough of this car! I can't afford to spend out on a new set of pistons and a rebore as that's what's really needed but its already 20 thou over size and I fear new liners would be required - more expense. Rob's idea is looking tempting. If it was my S Type that needed all this I'd flog a kidney to pay for it LOL.

I've tried to get it on the road for the last five years, last year I spent most of the summer welding the floor pans and toe boards after spending a lot of time sorting out the carbs and trying to get to grips with the engine noise with the stake down kit. I'd put the emoji - head banging the wall - but I don't have it .

[JCS]

NigelW

That sort of damage is often caused by the tail breaking off on a throttle plate screw. May I suggest at least a cursory check of the S.U throttle plates to ensure all the screws are intact. It may be that you have now rebuilt the carbs and not particularly noticed that the tail of a throttle screw was previously missing.

Looking at the damage it appears recoverable since the piston ring lands are intact and the bore would appear to be responsive to a very light hone with a flexi ball honer, given that the piston faces seem good. Clean the piston up in a lathe, you only need a light skim and that is really only for looks. If you need to loan a flexi bore honer let me know (I am away until next Tuesday)

I would have thought a set of rings, gaskets and head face may be your only expense if you are completing the work yourself. I am aware that suggesting repairs from a distance is not always helpful, but I hope you can recover it.

Norman