Found some pics of the bar and socket I was using on the pulley nut-thing
If it cannot be turned using that, turning it—if at all possible—with the ring gear is not going to stave off the inevitable.
Remove and rebuild the engine.
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If the problem that prevents the engine from being turned is caused by rust on the rings before you dismantle your engine try to dissolve the rust. Instead of pouring ATF. kerosene or Marvel Mystery oil down the sparkplug holes try regular classic Coca Cola. Coke is mild phosphoric acid and will and does dissolve rust. Worth a try at this point. Pete
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No…Coke is not the answer.
On top of that, if you were successful in “dissolving the rust,” the concomitant damage to all the associated parts is going to exist, and is unfixable by any chemical means.
Unless this project is intended to make a junkyard dog run… the onl real answer is to do it right.
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I’m keen on the Coke idea Pete55Tbird 
Please give an estimate of how expensive " to do it right" will be and EXACTLY what that means? Inquiring minds want to know. Pete
I’ve got no plans for any junkyard business. This engine has only 60000 miles on it. Was taken off road in mid-eighties due to unresolved fuel-supply problem.
Turned out that pipe inside one fuel tank was full of ‘mud’. It all fell out when I examined the fuel tanks in 1990.
This engine was turning freely with spanner on pulley until a few years ago.
I don’t think there will be any wear in such a low mileage engine but if it is dismantled to fee-off one or several pistons (or it may be camshaft or something) then you need at least a gasket kit, probably new cylinder studs and the heads skimmed.
If it can be freed off without dismantling I think it will just need flushed and filled with new fluids.
Impossible to say: in any case, I’ve been long enough away from doing this for a living, my estimate would be worthless.
There are members here who could give a better estimate: the minimum would be gasket sets, bearings, chains, chain guides, rings, valve seals, and perhaps a heavy honing of the rust damaged cylinders.
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Yeah, but a trip to a shop with a sinker EDM will take care of that.
Agree with wiggles here if its not moving with that bar don’t even bother with the flywheel. Engine out.
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Well when the engine comes out there’s no harm in trying it from the flywheel end. Saves spending 3 months trying to get the heads off 
Just a left field thought, how about an impact wrench on the crank bolt and somehow a long lever using the socket as a pivot piont at the same time?
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Vinegar, works on mild rust, evaporust woks on everything else downside to evaporust is it leaves behind iron oxide film
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Doesnt help. Ive tried it!
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Fair enough, Foxy - but with freely moving pistons, liner movement is not a prime concern. Dry liners are not very easily moved…
Frank
xj6 85 Sov Europe (UK/NZ)
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I believe the V12 has wet liners which just lift out. They are service items. I’m thinking if I disconnect big-end caps can remove any stuck pistons intact with liner them immerse them in ATF or something to separate them
I have successfully freed off a seized mgb gt engine years ago, after trying many different methods without success.
An old mechanic told me to pour boiling engine oil in through the spark plug holes, put the plugs back, and leave it for a few days. The hot oil forced its way past the rings to some extent, as the metals expanded.
Plugs out, lever on the crank nut, still not easy, skinned knuckles and swearing, but it did work.
The engine was only a four pot, so I stripped it anyway ( as you do ).
I know there’s 12 cylinders that are tight, but if you can’t turn it with a bar that long, you’ll have to strip it I’m afraid.i think even if you got it to turn, you could suffer broken rings.
Also corrosion in the bores could cause an ongoing problem. First thing to do is take off all the head nuts and washers. Introduces good quality penetrating fluid down the sides of the head studs. Don’t know how urgently you need to resolve this problem, but the longer you can allow the fluid to soak in - replenishing occasionally, the better!
Hopefully when you then do start to remove the heads they MIGHT come off more easily!
If the engine has always had antifreeze in it that does help a lot.sorry to be a doom monger but thinks it the best option.
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A lot of free advice you are getting tells you to “do it right” or you will be forever unhappy. I have never rebuilt a Jaguar engine 6 or V12, so I was curious as to what a reasonable cost might be. This link I got from the JAGUAR CLUB as to the cost, PARTS and MACHINE WORK ( NO LABOR ) for a Jaguar 6, 4.2.
http://www.jcna.com/library/tech/tech0003.html
This parts and machine work for a Jag 6 is OVER 4 GRAND. That’s without ANY surprises.
RECALCULATIMG, RECALCULATION… Pete
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Sure, Foxy - but then you are further into complications. You’re now looking into a V12 rebuild - which, as Pete says, is a different ballgame…
While the operation described can be done with the engine in car; the front subframe must be removed to allow dropping the sump. No great shakes as such, and worth while if stuck piston(s) is indeed the problem…
How far have you got with disassemblies and inspections…?
Frank
xj6 85 Sov Europe (UK/NZ)
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