I'm at over 105,000 miles and I am getting a bit of a rough idle until it warms up. I bought a new set of plugs [NGK iridium] and did a search for spark plug change on a N/A 4.2L. I watched the video from Vance580 and read the detailed instructions from Cliff328 and feel confident to do the job. I do have a question though - should I be using anti-seize on the spark plug threads? Cliff328 makes a good case - Vance580 put them in dry. I asked my parts guy and he said the plugs are plated and do not require anti-seize. I always use anti-seize on the plugs on my motorcycles. I suppose it would not hurt to use it on the 4.2L but thought I would put it out there before I did the change.

 

I would and I do on all my vehicles. Just a small dab near the top of the threads.

Be sure to not overtighten if using antiseize.

 

NGK say not to add any as they already have an anti-seize coating.

The old ones come out much easier if hot (or warm).

The rear ones are the hardest access so do 'em first maybe.

 

Wow, thanks for the warm engine tip - I forgot all about that trick. It does make a difference. I believe that I will install them dry per your and the NGK suggestion. Putting the install off until tomorrow when the rain stops and I can pull the nose into the garage.

 

It's best to only remove the spark plugs after a cold-soak for two reasons.

The brass inserts holding the coil units in place can separate from the cam covers when warm and the aluminium spark plug threads in the cylinder head can be damaged if the plugs are seized.

 

I'm sorry to say this but what is a "cold-soak"?

 

Cold soak means the engine assembly and fluids are at ambient temperature.

 

what size socket did you use to pull the plug ? is there a special set ?

 

Wow, that's a shock. I got one side's plugs out easily with a pretty hot engine then had to stop for quite some time and the others were a swine to get out cold.

Is the STR/V8 maybe like this and the 3.0 not?

I don't even recall any brass inserts!

 

I believe the OP has a car fitted with the 4.2 litre NA engine. The cam covers have threaded brass inserts for the bolts securing the coil units.

 

Ahh... so much simpler on the STR - though access is "awkward".

 

Sorry for the delay in answering your question - I was on vacation. I used a 5/8" spark plug socket with a 3" extension - a universal - a 6" extension - and a ratchet. This seemed to make the job go rather easily. I did the job cold. One piece of advice is you should have a short 90 degree Philips head screwdriver to remove the back screws on the engine cover or use a Philips head bit with an appropriate box end wrench.