Hey guys,

I just recently changed my sparkplugs (using NGK 5N10) on my 2009 Jaguar XF 4.2 N/A. The car has over 95,000 miles on it and the only issue I have are finding the rims being bent during tire changes which I just get them fixed.


Changing the Plugs was really easy it took me less than an hour and had no issues what so ever. They where easier to change than my 68 Cougar XR7. The only concern that I notice is that the wires going to the coil pack seemed to be very brittle due to heat of the engine I assume. I wonder if they sale a wiring harness to replace it and how much something like that would cost. I can see it being an issue maybe 50,000 miles from now. If any of you had changed the plugs yet what was your experience like??






My old plugs at 95,000 miles

 

Any chance of a write-up or at least pointing out any major issues, such as you did with the wires?

TIA

- Tim

 

How odd - my car has essentially the same engine & also IFR5N10 plugs but the wires were OK at 100K miles despite being years older.

Ohhhh, maybe they've changed wiring suppliers/quality

Main thing I found is the old plugs came out easily when the engine was still quite hot but got tighter when colder. (Access on an STR is awkward but doable.)

Someone else has already done a write-up of plug changes for the 4.2 -- might be for XJ or even XJR but it's the same engine in all major respects.

I needed UJs and extensions and I like to put the new ones in using a length of plastic tube (bendy stuff like for screen water) as you can feel whether the threads are lining up or not and ease the plug in the first bit.

 

This is what I did to change the plugs. I am going off the top of my head right now on how I did it

The list of tools I used.
-Phillips screw driver
-Flat-head screw driver
-1/4 inch drive ratchet
-1/4 3" extension
-1/4 drive 8 mm socket (I could be wrong because I did this 2 days ago but I know it is not a 10 mm)
-3/8 drive ratchet
-3/8 6" extension
-3/8 3" extension
-3/8 1" extension
-typical 5/8 sparkplug socket
-magnet to pick up the sparkplugs if your sparkplug socket doesn't have the rubber installed


Step one- I took the big plastic cover over the engine. There are 4 phillips camlock screws to take it off and make sure you take the oil fill cap off too. Then put the oil cap back on to prevent anything from accidently going in engine

Step two- I started on the drive side first (U.S) because I figured the spark plug under the brake booster will be the hardest part of it all. I took the plastic cover off that is over the valve cover. It is really easy to pull it off or use the flat head screw driver to pry it off.

Step three- I had an air compressor and I blew out any lose debris before I pulled the coil packs.

Step four- I remove and install one plug at a time before I move on to the next plug. The first 2 plugs closest to the radiator were easy to get to and I did not feel the need to disconnect the harness on them. The third and fourth plug you must disconnect the harness before you pull the coil pack to get to the spark plug. The sparkplug under the brake booster I just dropped the 5/8 socket in the sparkplug hole. Then with a 3 inch and 1 inch extension together I blindly connect the extension to the sparkplug socket. Then I connected the 3/8 ratchet to the extension when I felt the sparkplug was threaded out all the way. I disconnected the ratchet from the extension and let the sparkplug and sparkplug socket fall back into the engine. Then I pulled the extension out and used the magnet to pull out the sparkplug socket and the sparkplug. Installing the sparkplug under the brake booster was the same process but in reverse. I just drop the spark plug in the hole then the sparkplug socket (w/o the rubber installed). Then the 2 extensions (3 inch and 1 inch) together I used it to blindly connect to the sparkplug socket. Then by hand I threaded the sparkplug when I felt a sharp rise of torque. Then I connected the ratchet to finish tightening it.

The passenger side was just like the sparkplug under the brake booster times 4. So the passenger side took longer than the driver side.

Step five- installing the big plastic cover.


I never did a write up before so I hope this kind of helps and if anybody else has any inputs or ideas to make things easier please share your thoughts.

Thanks

 

I'll revive an old topic, since I recently replaced the plugs in my naturally aspirated '09 XF. My original intention, since the car is 7 years old, and has an aluminum engine, was to simply pull the plugs, give them a dab of anti-seize compound, and put them back in place. Having only 28,000 miles on the clock, I fully expected to see plugs in very good condition.....which 7 of them were.


One plug, however, appeared to have suffered a manufacturing defect, as the center electrode was extending from the porcelain tip at somewhat of an angle, and had been that way for a while, as the burn pattern on the porcelain had a distinct, offset pattern. So, since I discovered this on the second plug I had removed, and this isn't exactly a 15 minute job, off I went, shopping for a new set of plugs.


Most of what I went through, was the same as "Popok"s write-up, with a few exceptions. I removed everything that he mentioned. However, I started with the RH side of the engine (US version), as it appeared to be the most cluttered, so I wanted to get it out of the way first. I also removed the round vacuum reservoir that is on the RH side of the car, attached to the electrical component box, as well as the oil vent canister that is both attached to it via a plastic line, as well as pressed into the RH valve cover. There is enough slack in the "plumbing", to allow these two components to be safely moved out of the way, providing a LITTLE more work room. I also disconnected all of the coil wires at one time, and placed the harness out of the way. Again, this made a bit more working room.


As the plugs are deeply set in the cylinder head, and there are obstacles in the way, a single 6" or 8" extension can't be placed on to the plug socket, then placed over the spark plug together, on most of the plugs. I was able to get a 3" extension and plug socket into the spark plug well, where I then snapped another 3" extension into the first, and then placed the plug socket over the plug, and loosened the plug. I then carefully lifted the socket and extensions up, until I could remove the one extension, then lifted the second extension, the socket (with a plug retention rubber in it), and the plug, up and out. I repeated this 5 more times. The front two plugs on the drivers side of the engine (US versions) can be gone after with the long extension, right from the start.


While putting everything back together, I also coated the inside of the spark plug boots on the coils, with a dielectric grease called "Spark Guard". It's made by MSD, especially for spark plug boot usage. I also smeared some Permatex dielectric grease across the contacts of the coil pack electrical plugs, before snapping them back in place.


I'm pretty sure that the XF chassis is a "cousin" of the Lincoln LS, which I had, prior to this ZF. I have a factory shop manual for the LS, and it calls out 11 ft/lbs of torque, for the plugs, and this is what I torqued mine to. However, due to the tight confines of the engine compartment, I was unable to get the torque wrench on the two plugs that are the closest to the firewall, the rearmost one on each bank of the engine.

 

do you remember what the gag is for the spark plug

 

https://www.jaguarforums.com/forum/x...-4-2-a-176199/