Hi, new to the forum but not to Jags, I used to hang about on Jag-lovers back in the day.

[[[bare with it there is question about engines at the end :-) ]]]

I've recently been a very silly and bought a new-to-me to XJ12. I know this is wrong sub forum but todays question is regarding the V12 and figured it'd get more traction here.. sorry if that's a bit cheeky.

The car has been sat for a while in a very hot climate (Nice - south of france) , it was parked up with engine/ignition trouble in roughly 2012. By the time I've got to it'd seized more or less solid. I'm sucker and have been watching wayyyy too many you-tube car rescue videos. I've spared you the "what the hell do I do with this motor" post by reading/watching everything I can.

I pulled the spark plugs, and everything else in the valley bar the fuel rail. I've pour diesel down the cylinders repeatedly and that has been soaking in for three or four weeks now. Three cylinders on A-Bank and two on B-Bank the diesel just sat in there as a puddle wouldn't go passed the piston so I figured they're my bad pots.

I left a breaker bar attached to the crank pulley and rachet strapped it to a massive trolley jack (lorry sized). That's been in tension for about two weeks. It was still impossible to turn the engine - I had a very large friend come help and it was going nowhere. So I've sucked the diesel back out with a syringe and tube, then loaded it up with cans and cans of penetrating oil. Left that a few hours and tried the starter, still just the normal clunk nothing.

I was literally at the point of giving up and working out what to do with my expensive junk. (engine swap etc etc)

Today I left my "death catapult" (the trolley jack) in place and under a lot of tension - yeah health and safety would of had a fit - and hooked up a battery and booster. I engaged the start and got a familiar but I thought louder clunk. It wasn't entirely clear but it did look like the starter had managed to nudge the crank on a shade - which would literally be the first movement I've seen since buying the car. I wasn't sure so tried again and this time nothing happened it defo didn't move. BUT I then re-tightened the rachet strap and tried again. Sure enough the crank did move a shade.

Encouraged by this, I blathered every cylinder in penetrating oil, re-tightened the strap and did one click of the starter. Long story short(ish), I did several rounds of penetrating oil -> tighten the rachet -> bonk the starter -> pull the breaker bar back -> repeat. In a surprising turn of events this actually worked and eventually I got the engine to do a full rotation.

The starter can now relatively happily spin the engine unassisted.

I appreciate this isn't now a "throw in the plugs and away we go" moment. But the problem is now I'm kind of left with no help or advice. All the videos and posts etc discuss getting the engine spinning again... which I have now done. But I'm a little concerned how to proceed.

• Obviously the engine oil is now toast, its sat for at least 10 years then had a bunch of diesel and penetrating oil dumped in it. So oil and filter are a given. Presumably I'll want to give if fresh oil to get it started and then do it again more or less as soon as the engine runs.
• The amount of gunk on top of the pistons is remarkable, they seem to have a really large deposit of "coke" / carbon on them. I'm wondering what the best way to deal with this is. All I can really think is blow an air line down the plug hole.
• The piston rings, presumably they're still stuck in the piston a bit, I'm hoping the heat of a running engine will free them up, but is there anything i can do ahead of time.

I'm considering pouring diesel down the plugs again and turning over by hand let it soak. I'm assuming the diesel will now get to places it could before.

I appreciate I will then have to deal with putting the valley back together and then what the issue was that got her parked up in the first place, but I do have a fully operational XJS V12 that I'll be able to refer to, so I'm hoping that will be an easier ride. Shockingly the dizzy's vacuum advance was still free and pinging back.

So yeah, really I'm asking for any advice about the phase just after freeing off an engine.

1983 XJ12 He (lucas)
1989 XJS He (marelli)

All help greatly appreciated.

 

Having done basically the same on motorcycle engines, 99% chance that the rings are stuck/rusted/corroded to the pistons, and both are junk. But, a 1% chance that they might free up; I would mix 50/50 oil and acetone, fill each cylinder and let soak a day. Then turn crank a quarter turn by hand and repeat. After about 2 weeks, get as much out of the cylinders as you can (spin engine with starter, make sure you have something to deflect the geyser)- then do a compression test. If most cylinders are 150 or above, drain crankcase, new oil and filter, and fresh plugs- you should be able to get it to start. Start and run until warm a few times, and do a leak down test…
A lot of work, but still less than a rebuild or swap.

 

Oh that's disappointing to hear.

​​​​​​Well fingers crossed .

 

When you say you'd fill the cylinder half 'oil' half acetone. I'm presuming by oil you mean diesel not engine oil yeah?

 

I used motor oil…don’t think it matters.

 

Going along with RGK, mostly.

I would drop and refill the oil NOW, even elcheapo oil. You have10 years of God knows what, that the oil pump will circulate NOW, and the bearings and such are going to luv that, NOT.

Also, after all this time, the 3 o/rings associated with the oil pump suction/supply pipes will be serious toast, so pan, sandwich plate OFF, and replace, NOT a fun job in the car.

I use, and have done so for too long,, ATF and Diesel fuel (50/50) as penetrene, and it works. The left overs make good weed killer.

Rings will be knackered, no bets at all.
NOT what you want to hear, but facts is facts.

It will probably run, and comp test within some sort of spec, but long term, NAH.

Did this with a Pre HE too long ago, and yes, it ran, and ran OK. It had stood in an Orchard for 7 years. A running S/H engine was $550 back then, so a no brainer. The old is a boat anchor somewhere off the coast.

 



 

I like to use Acetone and Dexron III in a 50/50 mix. Works surprisingly well. I'm more optimistic about getting the engine running again, but I doubt compression will be great. Also agree about changing the oil and filter right now. I'd also consider dumping some mineral spirits into the crankcase and spinning the engine over (without starting it) to try and release as much of the gunk in there as possible (take out the plugs to do this).

 

I did that once to a 1930 Model A pickup
Acetone and ATF. Took more than a month of soaking and trying to hand crank it over
Eventually freed up and I pull started it. ( using a XJ6) Smoked like crazy but after a few hours of running it, the smoke went down to almost acceptable. I could actually use the starter to get it running.
As a running vehicle It went from $1500-$3500

 

I think what you really want is an iron chealting agent. There is a product here called Evaporust and it chemically converts the rust and can free up many rusted together parts in a way that diesel or acetone won't. I'd put some of that down the bores, let it sit for 24-48 hours, suck it out and see what happens.

Evaporust is non toxic, don't confuse it with an acid rust remover.There are other brands, get one that uses a chleation reaction to do it's work.

Maybe you can get this product in France? https://www.rust.co.uk/rustbuster-sa...rust-removers/