Hi all.
now in the process of changing the plugs. I have cleared out the valley and removed the compressor (No gas) so got plenty of room. I wanted to clean it all out anyway. 9 plugs out fairly easy and changed. I have 3 to go all have moved a bit so at the moment they are soaking in some penetrating oil. I have purchased some PB Blaster so will have a go with that when it arrives. Been reading good things about it. All the old plugs are champion with the exception of the front A bank which is an NGK. God only knows when these were last removed.
Rob.

 

The joys of the "catch up".

I use Diesel Fuel/ATF as a 50-50 brew, and let it soak.

If they have moved, as you say, I would wind them back, after the soak, and then out again, SLOWLY, and keep working that way.

Snapping one off is really not a good situation.

 

Put a socket on the plug that will seat against the hex on the metal shell, or a piece of pipe that fits over the porcelain and seats against the metal, and use a hammer to smack it straight downward a few times. Then try to turn it. Don't get too carried away or you could damage the head.

 

I really would not do that! Just be patient and tease it out as grant suggested would be safer, i believe.

 

Hmm not to sure about smacking it. All 3 plugs move a bit so in theory the penetrating oil should work its way down the threads. It doesn’t really matter how long it takes as I can’t go anywhere at the moment.
Rob.

 

Acetone and brake fluid is another good penetrating combo

 

If they all move a little, I would go with PB Blaster. Some light tapping will help loosen carbon on the threads and will not hurt anything unless you really get carried away. If you can control the heat and avoid fire, heating the plug shell and allowing it to cool can also break the bond between the plug and the head. You may need to chase the threads when the plug is out. If you use a commercial plug thread chaser, be careful not to go too deep in, it is sometimes possible to bend a valve. I would suggest taking an old plug that has good threads, use a Dremel type tool to cut 3 grooves in the side, similar to a tap, coat it with grease to catch debris, and run that in and out of the damaged plug holes. That will not go in too deep, and will prevent valve contact. use compressed air and a blow gun with a long tip to go down into the cylinder and blow so air, and any debris, goes out the plug hole. Then coat your new plug threads with anti-seize, and install it. Reduce torque by about 20% for having lubricated threads. Good luck!

 

Hi Robbo

I'm with Greg on that one

When I did the Plugs on my Car it took me 3 days!

One Plug out then one plug in and whatever you do, just make sure that nothing drops down those holes, or its 'game over'

The Plugs on my Car were so tight that I had to use a Torque Wrench to get the leverage to get them undone

Then when you put the New Plugs back, they only need to be 'nipped up' plus about 5 degrees

Changing the Spark Plugs on my Car 'Cherry Blossom' Changing the Spark Plugs on 'Cherry Blossom' my 1990 XJS V12 and also removing and cleaning the Injectors

 

No hurry. I done exactly as you said one out new one in until it’s just seated then another 5mins of the clock if you know what I mean. Been cleaning the valley out as well it was filthy. I can’t understand why people would buy a car like this and not bother to maintain it properly. Bloody ridiculous.
Rob.

 

When they were new the xjs was aimed at a wealthier market... I dont like making assumptions or overly broad generalizations, but aimed at a market that might not have been as comfortable gettig thier hands as dirty. Then, specially in some markets, for reasons, shops were charging people AhMillion $$$ bucks for repairs on a car that needs a far amount of attention - all adding up to what we are seeing. Neglected dream cars. Shoot, Me... I have to be happy (kinda) about the way it all played out. For not much and a few skinned knuckles I think I am going to end up with a dreaM of a car - a car that FOR NO GOOD REASON was headed for a crusher...

Oh and - enough of my blabbering. There are some things I will wack on (lots actually) and there are things that I wont... Spark plugs, in an aluminum cast definitely land in the things I WON'T category... Also, I (and this is just me) would not and would NOT be looking forward to the day where I am tapping new threads (shaving metal) in a cylinder head while its still on the car. Nope, not me. A small dusting of aluminum shavings sitting on the top of each cylinder just WAITING for action at the first turn over.

If they are already moving some, and you can get some acetone and atf, PB or the like on them (a pool in those wells) and leave them for a spell, rock them back and forth gently for a couple of days, they will come right out. Dont be affraid to go a bit in the direction of TIGHT in the process of loosening them up. It makes it so you dont have to DRAG the gunk up the thread as much...

Its gunna be alright.

 

Hands down the BEST penetrating oil is SiliKroil, or AeroKroil.
Its available from them
Penetrating-Lubricating Oils
and even Amazon has it.
You'll be amazed and never go back
Bobmo

 

As with any repair on any car, trying to rush through it will result in problems. These cars are the "mother of all frustration" take your time, especially since the motor is already cooperating with you, it's just making you wait a bit.

 

BEER O'CLOCK, has a whole new meaning when working with a V12.

Under the current conditions, the beer truck has priority in our suburb. Followed very closely by the Krispy Kreme van, oh joy.

 

And, as a bonus for dedicated gear heads, the Aerokroil has the most delicious aroma.

Quite expensive, though. I reserve it for special occasions.

Cheers
DD

 

Yessssssssssssss. One out two to go. Both moving.
Rob.

 

Awesome! I've been kinda,,,,
Where did ya go!?
Have an AM beer after that first one and,,, then 9more?
Where ya at???

 

Hooray. Second plug out. One more to go. This last one is a bit odd as it’s an NGK all the others were Champions.
Its moving so again it’s a bit of a waiting game.
Rob.

 

not odd at all, PO had given up ( or garage mechanic ) and left the old ones in there at a service

good job your replacing all 12, just imagine how old some could be

BB

 

I
COULD
NOT
RESIST!

 

Still struggling with this last plug. Turns about 3/4 of a turn then locks up. I have just run the car up to temperature and gave it a squirt of penetrating oil. I’m hoping this might draw some down the threads as it cools. I thought I had buggered something as it wouldn’t start just spluttered then I noticed I had the coils connected to the distributor the wrong way. Changed them over started no problem.
Rob.