Sorry if this has been asked, but I have searched the site and the owner's manual. What is the type number and best make of spark plug for a 2003 UK 4.2 normally aspirated V8. I presume the answer is NGK iridium, but I cannot find the type anywhere. Also, is there anything wrong with using copperslip as an anti seize compound. And finally, does anyone know why iridium is used? It's dense and beautiful, but why on spark plugs? Thanks

 

NGK is the stock plug manufacturer. You can't find the correct plug in parts stores? Guessing iridium is super conductive and doesn't easily breakdown?

 

Thanks, but which ones?: BKR6EKC are the type for my car (not a Jag), I can't find this info anywhere for the S-Type V8

 

Agreed. Iridium holds up far longer under the harsh conditions a spark plug is constantly subjected to than any other material. Iridium plugs easily go 120,000 miles on well-maintained vehicles, and I've done more than 150,000 miles on a couple of sets in two Lexus SUVs before I sold them. I've read claims of guys doing more than 250,000 miles on iridium plugs and they're still looking good and going strong....

My philosophy is this: If I have to pull the intake manifold off just to change the plugs, I only want to have to do that one time for the duration we own the car. So if the intake manifold comes off, iridium plugs go in. I believe it saves me both time and money in the long run....

Have you checked for an application guide on ngk.com?

 

Exactly. The ONLY advantage of exotic material spark plugs is durability, and nothing to do with performance. Modern cars are required to meet anti-pollution limits for an extended period of time and mileage. Having a plug that works just as well at the end of this period as it does at the beginning is part of it. The movement away from points and coil ignition to modern HEI and carbs to EFI was initiated by this requirement also.

An acquaintance in Florida has a set of plugs that were removed from a Ford truck at 400K miles, still working fine.

 

I suspect the ones for the STR would be fine NGK IFR5N10

 

Just ask the parts counter for the cross reference for your car and plug. Wait, use the "search forum" feature (on this thread). We mention the NGK plug part number several times. Just type in "NGK plugs", etc.

 

Jagv8 beat you to it.

 

Thanks. I am afraid I don't trust the motor factor parts shops to be always correct. Further to all of this, does anyone know where I can get a workshop manual for the S-Type?

 

You can download the repair manual. jagv8 will fill you in....

 

+1.

The EPC calls out Jaguar part number C2A1535 or AJ84575 which both cross references to the NGK number shown above.

NGK Partfinder Product Cross Reference

 

JTIS is on here. Also JEPC

 

sorry, didn't understand most of that. Do you mean "put details of the model and year somewhere so that it shows up underneath my name" Because I have entered these details in 3 places so far

 

...and I did mention "2003 S-Type 4.2 normally asperated V8" at the start of the thread. I am trying, honest I am.

 

sorry, "aspirated" keyboards can be as difficult as computers at 11pm

 

Use the ngk iridium because the tend to not foul .

 

Don't, in this life, or any future life, use antiseize on the plugs. I'm going to
quote a few lines from the December issue of Motor Magazine, a magazine
dedicated to professional mechanics.

"So, we add a dab of antiseize and everything is fine, right? Wrong, and here's why. Spark plug manufacturers are constantly improving their products, and they recognized the potential for galvanic activity many years
ago. Today, virtually all spark plugs feature some tiype of plating on the threads. Nickel, zinc-chromate or other proprietary plating processes are used to plate the threads on the plugs from various manufacturers. Regardless of the material used, the purpose of these platings is the same-
to act as a 'lubricant'.

Small particles of the plating may break away from the plug threads during removal. This is normal. It keeps the plug from seizing in the head and prevents damage to the plug and/or threads in the cylinder head. Adding plating to the threads makes the use of anti-seize or any other lubricant unnecessary.

So, is there any problem possible harm adding anti-seize to the threads?
Yes, plenty. Lubing the threads may mean you're overtightening the plug by 20 to 30 percent. And, depending of the chemical composition, anti-seize may serve as an electrical insulator rather than a conductor, forcing the coil to work against this unwanted resistance, or it may become overheated and damaged."

The article goes on the explain other problems associated with using anti-seize. The article ends by saying, "check the gap, then install by hand with
no added lubricant of any kind, then use a torque wrench to tighten the plugs to the vehicle manufacturer's specs."

The article has a few photos and mentions that most OXYGEN sensors do require anti-seize and some manufacturers even coat the threads before
the sensors are shipped; however, the spark plug photo indicates that,
"..regardless of the cylinder head material (cast iron or aluminum), no
anti-seize lubricant should be placed on the threads."

It's your vehicle and your cylinder heads. I'd check with the plug manufacturer before installing.

Cliff

 

You may wish to believe evrything it says in Motor Magazine,however I prefer to look at the Service Manuals for the vehicles I work on.

In the case of some Jaguar engines, the Jaguar Service Manual specifically recommends the use of high temperature nickel anti-seize on plug threads,but as it happens not for the 4.2L V8.

Other car manufacturers also recommend the use of high temperature anti-sieze lubricant on spark plug threads in some cases.

 

In addition to service manuals, there is also hard won experience. More experience than it takes to search/copy/paste an article for $0.50 a word.

Overtightening is *not* a problem if one consults the manufacturer literature and takes note of the adjustment required if lubricant is used. In addition, if one uses torque to angle, the torque value itself become completely irrelevant.

Ford installed spark plugs without lubricant on certain heavy duty engines with aluminum heads. They now also have a TSB out on the special removal procedure to avoid pulling the thread out of the spark plug hole which in turn requires a new head or helicoil thread insert repair. The TSB also calls for lube on the replacement spark plugs. Manufacturer TSB's are carefully researched documents written by engineers that address known problems produced at much greater cost than magazine articles slapped together to meet a deadline.

I use lubricant, have always used lubricant, and will continue to use lubricant. I also rarely use a torque wrench.

 

so is copperslip OK?... and what is the tightening torque? 25Nm? Oh, and I found a manual on e-bay for £5 ($8) ....Thanks