I pulled out the stock NGK Iridium plugs with 70,000 miles on them and installed new Bosch Iridium plugs. I unbolted and moved the coolant tank to gain better access on the drivers side, one side of it is held in place with a plastic bracket that I could not seem to maneuver the tank enough to free the bracket, ended up breaking the bracket. I drilled a hole in the remaining part of the bracket and zip tied it to the tank when reinstalling, there is still a nut on a stud and a bolt holding the tank in place, no big deal. A swivel is required to access the plugs, there is not much room on either side, the rear plugs are a PITA, the stock plugs were tight and difficult to remove but they came out.

Attached is a pic of the plugs I took out, there is a hard white substance built up on the electrode on most of them, they still worked fine but for the price of $31.84 shipped after rebate for the new plugs and about 3 hrs work start to finish it was worth it to me to change them out.

I used anti seize on the threads of the new plugs and they easily turned in by hand and then I snugged them up with the ratchet. I put a bit of di-electric grease into the plug boot with my little finger and spread it around, the plug boots slipped nicely on to the new plugs.

All in all not a terribly difficult job and the average do it yourselfer should be able to do it, I did curse and swear a bit, mostly while removing and re-installing the coolant tank!

Started it up and it ran perfect!

 

any reason why you went with the Bosch's over the NGK's?

 

Plugs look a tad lean. Unless the camera flash just makes them look white. Grey tan colour is more normal for other engines I've pulled plugs out of.

 

Everywhere I checked the Bosch's were half the price of NGK's. Figured Bosch wouldn't be cheap quality, hopefully.

 

The color is kind of greyish, I recently ran a couple bottles of fuel injector cleaner thru the car, don't know if that would make a difference. The engine and ecu are stock.

 

I'm curious why you changed the plugs @ 70k. I was under the impression Jaguar changed them @100k on the 4.2’s .

The whole zip-tie thing has me shaking my head . If I was in the market for a car and saw a zip-tied fix it would make me question what else might be super glued/zip-tied/duct taped or rigged.

You are from NASCAR country; we are supposed to set the example !

 

My personal feeling is that the car companies have stretched out their maintenance intervals as a means to sell more cars (look how little maintenance our cars require!). For my peace of mind I changed them out and it may all by in my head but man it sure feels like it runs better and that is good enough for me. I also changed out every drop of fluid in the car, makes me feel better and that is the most important, it doesn't cost much financially either.

I had to zip tie it in place until I can buy a new plastic bracket, even so putting that new bracket on is going to be all but impossible I think, it is in there in such a fashion! There must be a way, I won't leave it that way but to make it driveable safely I did what I had to do, isn't that the true spirit of NASCAR country?

I agree with you, I would never buy a vehicle that looked patched together and would never sell one that looked that way either.

Thanks for reading!

 

Don't knock zip ties. They are extremely cheap, very robust, easy to instal, reliable and simple to remove. They also make convenient handcuffs for those in authority!

A nylon zip tie not exposed to UV degradation will last for over ten years. You'll find them all over a modern car, from the factory.