I have my grandfather 85 Series 3 XJ12 vanden plas edition. Now I know there are many purist on sites. But what is the rarity of it and value?

I can pull my hair out trying to fixed the current wiring situation and try to get the v12 out. Or I swap in a lsx.

Now my question is what would be the best route to take, taking into consideration this is a Vanden Plas HE model.

If it was a i6 there would be no questions on to lsx it.

 

This is a not uncommon question on here, ie the Jag motor is not running, surely it's easier to swap it out with a V8 motor.......

Honestly speaking, an XJ12 is a nice car, but it's not "rare" and unfortunately they are not really worth much as most people tend to be afraid of them.

Also, the value of a car like this is 20% it's spec (ie V12) and 80% its condition. You have a non-running car, so the value is scrap metal or parts. So, on one hand, fire away and rip out the V12 and stick something else in there. You can only make it worth more if you get it running. On the other hand, the difference between running perfectly and not running at all is usually a single wire. The challenge is finding that wire, but I think I would spend at least some time fiddling first before I decided on an engine swap.

Give us the basics....... it doesn't run....... does it crank ? does it have spark ? does it have fuel pressure ? does it ever splutter or try to start ? does it start when you squirt starting fluid into the air intakes ? etc, etc

 

A Ser III V12 is rare in the USA and considered pretty desirable as a result.... if it's in really good condition. An average/poor condition one is "just another run down old Jag".

Value? In dollars? Probably not very much if in average/poor condition.

An exceptional example in mint condition might bring $8-$10k in the USA. An average axmple less than half that amount.

Is the engine not running?

I'm not much of a purist ...do whatever you want with it.....but if it has wiring problems how is an engine swap gonna solve anything? Most the wiring problems can be sorted out pretty easily on these cars. Not all that big of a deal.

Cheers
DD

 

if the engine is mechanicaly sound, it is worth tracking down and fixing the no run issue.
If has a dropped valve or two and/or leaking or blown head gaskets, the choice to swap becomes more enticing.

A compression test is as good a place to start as any. But, I think it may not be easy on this engine as installed. At times, one can feel hear cylinders as the engine is cranked. Very irregular means no resistance by compression in places ,if low or no compression ion one or more cylinders. Easy on one two or four bangers, not so much on those with more cylinders.

A look or feel of the coolant and oil can tell a lot. Rust brown goop or clean blue, yellow or green!! Same for the oil, emulsion or merely black? Gritty feel or nicely transluscent?

And, a jump start. Jump battery + to the coil plus. Squirt some start fluid in the intake. Crank it. Yopu want a fresh fully charged battery so as not to be mislead. If it fires and runs even momentarily, there is room for hope. If not, not so much, but all is not lost. At times, another 12v battery in parallel is needed to get a really good crank. That may awaken a sleeping engine. In olden manual days, a push start did it at times!!

 

when I went to go look at a jaguar that "didn't run" all I did to test drive it was swap the battery for the one in my truck and tighten the loose alternator belt, then VROOOM! it could be that easy in the end.