This was a fiendishly difficult job. Broad steps are below. Electrical connectors, clamps, clips, hoses, and factory torque values have been omitted.
A little earlier than the scheduled maintenance. Use profile may justify doing it earlier than the prescribed 63,000 miles. Seeing the plugs and feeling how they came out, I think this sort of time-frame is reasonable.

Parts needed
6 Spark plugs. I used OEM LR178881

Special tools needed

• Spark plug socket
  Spark plug socket
• Wiper Arm puller
  Wiper Arm puller

Steps

• Verify spark plugs are correctly gapped. 0.6-0.65mm. The OEM plugs LR 178881 should be correct from factory and should not be adjusted.
• Disconnect battery
• Support hood and remove struts
• Remove Wiper arms and place to side.
• Remove front cowl
• Remove Air duct
• Remove Engine Cross-member
• Remove Front secondary bulkhead
• Put the Charge air cooler into service position. (This was a nightmarishly difficult step due to the short hoses)
• Remove ignition coils
• Remove spark plugs
• Replace spark plugs with new.
• Reinstall ignition coils
• Reposition charge air cooler. Again insanely difficult.
• Replace all the removed stuff in reverse order.
• Beer

Looking into the spark plug housing and the cylinder below.


This hose was a nightmare to remove and re-attach




All back together again

 

Ack! massive amount of work! Well done! I'm not sure I'd have the patience or courage.
Can anyone remember when ACCESSIBILITY for service was a design feature?
Things have changed from in-line 6 cylinder in the 1956 ford pickup dad and I rebuilt

 

Yes. A complete epic. I really thought it had bested me a couple of times. Before removing the hoses on the intercooler I almost packed in and gave up.

And then again trying to get the same ######*€%ing hoses connected I was wondering wtf I was thinking.



I feel like I’ve been in a brawl today.

 

I was wondering -- upon driving, did you notice any improvement in drivability / smoothness / throttle response -- or other improvement?

 

Thanks @GavinC for taking one for the team! Mine is at 57,000 miles and I was going to tackle my maintenance at 60k. This reminded me when I was a much younger lad when I replaced the spark plugs out of my Dad's 1991 Nissan 300z twin turbo. I had to remove half the engine just to see the spark plugs. Now that I know what's involved with PITA, I'm gonna buy my favorite scotch as motivation to start this job.

 

Seems just the same. I wasn’t noticing anything untoward before the swap.

I had checked with my GAP tool for any misfires. None of any significance noted.

All driving very smooth today.




GAP IId tool live values misfire count.

 

I would suggest 2 bottles

 

Gavin, you’ve done it again. I’m sure this comprehensive guide will be of help to many people going into the future.
Sticky?

 

Thanks mate. Much appreciated. Hopefully it will be of some use to some folks in the future. I tried to title the thread to make it a big more googleable. Not really worth being a sticky I reckon. Too niche. I put it in my home servicing thread too. That one covers more routine, easy to do DIY and more widely performed stuff. That might be sticky worthy.

• Oil changes
• Filter changes
• Brake Flushes
• Tire rotations
• Diff and transfer case drain/fill
• $3 Wiper blade refresh

All easy items that can save you a ton of cash and are fun to do. Land Rover owners often become home mechanics by default. lol

Had the ancient Greeks been Defender P400 owners, Sisyphus wouldn't have gotten off so lightly. The gods would have an eternal supply of charge air coolers to de-hose/re-hose.

Go Maroons!

 

I am about to take on the same task. Thank you for the write up this is going to help.
I purchase the OEM NGK spark plugs from NGK.com and I was able to get all 6 of them for $80 and some change.