Changed the spark plugs today - some questions
 

I finally got round to changing the spark plugs today. Found it fairly straight forward, the hardest part was getting the plenum covers back into position! (I took a fair few photos if anyone needs a rough guide.)

Anyway, most of them looked OK with a light grey, browny colour but this was the state of one of the plugs, any idea why it's like this? It was from the front right (think it's number 5 cylinder) so would be under the oil filler cap, could some spillage have got in their somehow?

BTW, car has done 50k and is 8 years old and I'm guessing they're the original plugs.

http://farm5.static.flickr.com/4009/...3f97061cd9.jpg

Sorry, this was meant to be in the Technical forum so if a mod could move it if needed.....

Done.

A few photos would be good.

Stuff can get down there and there is no way out for it. I am surprised nobody has replaced the plugs in all that time. Key question is what did the plug electrodes look like ? This can tell you a lot about the conditions in the combustion chamber

Thanks for the replies. I'll assume that the strange contamination on that plug is due to a bit of oil running down from the filler cap, especially as the electrode seems normal (I think). As for the plugs being original, well the car has no history with it at all and has been a bit neglected in the past, so I'm doing my best to get it back to a decent state!

In case anyone is looking for some info on this, it took me an hour and a half to do all six and required little more than a basic socket set with 5" and 10" extension bars. I also have a 'mini' socket set for removing the smaller bolts. I removed the rubber bung from the spark plug socket as I have an extending magnet thingy for pulling them - also comes in useful when you drop your sockets/bolts/screws deep into the engine bay! :) Oh and this is the first time I've replaced spark plugs on any car so I'm not experienced at this at all!

Here are a few pics that I've tried to annotate a little;

This shows the three panels that I removed after removal of the acoustic engine cover - so four bits to remove in order to gain enough access.

http://farm5.static.flickr.com/4039/...cd39c58b90.jpg

This shows the location of the seven bolts that need to be removed from the coil packs. (Three on one and two on the others).

http://farm3.static.flickr.com/2775/...eaed002646.jpg

And this is what the electrodes look like. Pretty normal as far as i can tell.

http://farm5.static.flickr.com/4029/...24315df3a9.jpg

This just looks like some oil has got into the plug socket. The tip of the plug looks okay.

The plug electrodes you showed in the photo looked Ok to me, I have seen worse !

Plugs last much longer than they used to, in fact Jaguar recommend changing them at around 70k miles !

A little bit of Copper Grease "will help.. in a most delightful way"
 

Did you rub any copper grease on the threads of your new plugs?
Copper grease is a high adhesive lubricant and anti corrosion agent that can withstand high temperatures and prevents the spark plugs from seizing in the engine. I use the Wurth product and was pleased to see that my Rover Service Centre also uses a number of Wurth's products in their workshop - including copper grease.
I don't claim to be an expert, but have heard that some old plugs that have seen 100,000 kms service in the KV6 engine have been a "real B" to extract.
egremont.

Thanks for the replies.

I agree, I think the condition of the plugs is OK, no real wear and little in the way of deposits.

With regard to greasing the plugs, I actually smeared a bit of engine oil round the threads but in hindsight that will probably just burn off. Oh well, I do 30k a year so they won't be in there too long!

It's good advice on the copper greese.. Many garages do this just make sure you don't use to much..