This weekend I decided to try changing the spark plugs myself on the V12, and while I was at it, do the modification of the distributor, new cap and rotor, and replace the leads with the Denso 8mm wires.

Holy guacamole!! Even after reading numerous threads on the task to prepare myself… you just can’t prepare yourself for what you’re going to be up against. The next morning I hurt in places I didn’t remember having.

However, I did learn a few things:

1. For all the times I’ve paid someone to do this before, it wasn’t enough.

2. After two decades, Jaguar engineers couldn’t freak’n bother to redesign the throttle pedestal so it doesn’t take a clairvoyant contortionist with an unlimited tool chest to remove the two aft bolts?

3. I’m too tall for this task, or too short, can’t decide which.

4. The people who claimed to have done this the first time in only a day or afternoon, obviously have some super power I don’t possess and should contact S.H.I.E.L.D. immediately.

When the beast fired up immediately with the turn of the key, believe me, nobody was more surprised than me.

 

I have to disagree with you, people make a big deal out of this, and I think it is just because its a common maintenance thing, so many people have actually experienced it. I would definitely say its exaggerated, so I don't agree that its worse than people make it seem.

Most of the plugs come out pretty easy, and the plugs are easy to keep up with. The AC pops off really easy and then those front plugs are easy to get to. The worst are in the back, but they just take a bit of extra time.

Honestly the worst things about the job noone ever mentions, they make it seem like actually changing the plugs is hard. Getting the throttle tower off can be a pain in the ***, but you can change them without doing it and getting the old rotor off can be pretty hard, but you can always just break it off, since its being replaced. The first time I did it, I didn't have a swivel socket to take out the bolts for the tower, so I drilled holes in the top of the pedestal to put an extension through, you can't see it after everything is back on, and its just a little bit of aluminum, so w/e.

Its like a half hour to 45 minute job if you are making sure to keep clean as you go. I've spent that much on a honda before with 4 plugs, so mehh.

 

If I had to go do it again this weekend, I agree it's not so hard and it would go *a lot* faster (particularly since I modified the throttle pedestal to make it easier).

I don't want to discourage anyone from doing it, just wanted to vent a bit about how I struggled with it the first go 'round.

 

HUGE amounts of JD PRIOR to starting this adventure works for me.

The pain is unfelt
The bleeding is un-noticed.
The silly smile on the face at the imposing problem is priceless.

In other words, YA GOTTA DRINK MORE.

 

Having said that I trecently changed the spark plugs on both the S Type V6 engines.

The INLET manifold has to come OFF to do the 3 on the A side, REALLY, that was an engineering marvel at the very top level.

Granted, they are 100K plugs, but still, fair dinkum, DUMB.

 

The intake manifold? Seriously? OK, the V12 isn't so bad.

 

I also recently finished this same project - Plugs and wires, cleaned the cap and rotor instead of replacing as they didn't seem in bad condition.

I'd fall somewhere between your and sidescrolling's views on this - yes it was a pain but not what I'd call terrible, on the other hand there's no way in hell I'd get it done in 1/2 - 3/4 hour. A lot of the time I spent on cleaning as the bottom of the vee was heavily covered with oil/grease/dead bugs plus a bunch of bird food that I believe was left by the mice that ate the old wires, I don't think it had ever been cleaned before. I also spent a lot of time stopping to take photos to aid me in putting everything back together. But even if it was clean, and having done the whole thing once now, I think it would take me at least a couple hours. I guess practice makes perfect.

 

A friend's Mitsubishi Triton requires the inlet manifold removal for a plug change as well. (maybe designed by an ex jaguar engineer hahaha!)

 

Then add the price of inlet gaskets, or o/rings, depending on MYear, and another $100 to the cost.

Then the real smack in the mouth. A new top radiator hose, coz as sure as hell is hot, you are going to break that bleed hose plastic nipple, so $125+ to cheer ya up.

Who puts plastic in pressurized cooling systems??, ALL OF THEM, it is part of the built in obsolescence we dont want to accept.

Time for a JD.

 

I much prefer changing the plugs on the v12 to many transversely mounted engines. Even a little v6 has half its plugs stuff into the firewall.

Honestly the thing I hated the most about doing the v12 is checking that many gaps, its tedious, not to mention feels pointless until you find that one in the 12 that isn't correct out of the box.

I have and use the jaguar tool, which seems pretty cheap but it seems to work better than using an actual socket with a wrench and even a swivel on it. Maybe thats the secret? The socket grabs really well and since its just pinned together its really thin and easy to reach in with.

 

That tool is particular helpful for reaching the plug in 6A, I don't think you could get a standard plug socket on it without modification.

 

I used a regular spark plug socket for everything, I think for 6A though I used either a "u-joint" adaptor or a wrench on the hex end of the socket. Once I got everything else out of the way the plugs were pretty simple, it was removing and replacing all the other stuff that was in the way, plus cleaning up 24 years of grime, that took so much time. I don't think I have the factory plug tool, maybe it would be even better.

 

I've always found that all 12 of them are completely out of spec right out of the box, since the NGKs I use are factory-gapped at 0.035, and the requirement for the HE motor is 0.025

I despise the job. It takes me at least a day to do it, and I always put it off as long as possible.

I did, however, modify my throttle pedestal, so that it is now easier to work around, and remove.

 

That's an impressive looking Throttle Pedestal there JagZilla!

 

I was really surprised to find that the plugs I just installed - NGKs purchased from Rock Auto - were all correctly gapped as I received them. And I agree, even just checking them all was tedious.

That's a great looking throttle pedestal! Nice job!

 

Do you have any advice for removing air conditioning compressor. ?
Three bolts have very easy access.
Fourth is obscured by cooling system pressure cap on crossover.

Any suggestions welcomed

 

What year is your car?

I just looked at mine, and neither the pressure cap or crossover obstruct access to the two front bolts.

 

The same here, removing the compressor was pretty easy - 91 v12. Reinstalling was a bit more fiddly for me, finally found that the right front screw had to go in first to get the other three to line up, also be careful about pinching wiring between the comp and the valve cover. Otherwise pretty straightforward.