Xjsc 1985 - not driven since 1994..


New Member
Jun 16, 2020
I am a newbie here and also to the intricacies of the XJSC.
My XJSC has been parked up and not started since 1994 and with the CV lockdown I have finally had some time to start looking at it.
I took a chance and stuck a new battery on turned key to see if it would turn over but just a strong click from the starter motor area and nothing turned.

I did some reading and removed the AC compressor and cruise control bellow and took all 12 plugs out and poured Marvel Mystery oil into the piston chambers. I got 11 out first time and then left for 3 days and then took last one out and left that one a couple of hours and tried to turn manually by the crankshaft bolt. But it was absolutely stuck and would not budge.

I do not know if I need to give the last cylinder time soak and try again or if I have major engine problems.

I am getting the welding and bodywork done on the car and a few guys from the industrial estate have been tuning in. One said the engine is seized and it needs to be replaced. The second guy said I need to take the engine out and get it overhauled as there may be common faults that need to be rectified and that whilst it is out, all looms can be checked and gearbox and clutch plates checked and also engine bay checked and sprayed. The third guy said, just buy a second hand engine and put that. My immediate thought was the fear of getting an engine that might fail shortly after installation which would be disastrous.

I am clueless as to what is best. I just want the option that will last and give me (hopefully) the least amount of problems later down the line.

If the second option is the best, is there anyone who I can take the engine to for it to be overhauled?

Many thanks


Thanks in anticipation of your help.


An Unfortunate Discovery
Feb 17, 2006
Left a bit, no right a bit, just there. England.
2020 Tesla Model 3, 1990 Discovery 1 Bobtail
OK so if we start from the point where the engine is dead as it currently sits there's nothing to lose by trying more steps to revive it where it sits. As long as you don't break anything in the process you won't make the process of rebuilding any more difficult and it certainly won't make a jot of difference if you were to get another engine anyway. I can't decide if that oil seems thin enough to penetrate but after some time it may have done its job and will allow a little movement. You could maybe thin it down some more with petrol, maybe remove the heads to get a better look.

Some sources online suggested running hot water through the block to try and expand it, the cooling system would have to come off for cleaning anyway so maybe worth trying?

I would personally want the existing or replacement engine professionally rebuilt if I wanted to keep the car and make it reliable, we all remember the mess that was James May's XJS in the cheap coupes challenge. If you try and run it as is you'll definitely have issues. I don't personally know any companies but a search brought this eBay ad up quickly:


I suspect a full rebuild won't be cheap but it's an old Jag, it was never going to be cheap.