Hi all

Just had my 2006 4.2 S/C serviced and MOT'd at my local indie.....sailed through with no advisories, however.....
The mechanic said he hasn't changed the spark plugs that were in the service kit as he was scared of breaking the old ones removing them, said they were incredibly tight.
He also explained that the reason this can happen is because of all the carbon/crud build up on the bottom of the plug thread which actually protrudes slightly into the engine block prevents the thread from turning.

So my question is is there an additive that i can add to the fuel to help clean the thread to enable easier removal?
I should add i only ever use BP Momentum or Shell Optimum fuel

Is this a common problem and is there any advice from you good people out there?

Also i do not have any issues with the current plugs

TIA 2015 L494 SDV6 3.0 HSE Dynamic
2006 L320 4.2 Supercharged
2009 BMW X5 M-Sport - Gone
2007 L320 2.7TDV6 SE Buckingham Blue - Gone
2011 Jaguar XFS 3.0V6 Diesel - Gone
2009 (59) L320 Facelift 3.0TDV6 HSE White Wrap - Gone
2008 BMW X5 M-Sport - Gone
2005 Audi A6 3.2V6 Quattro S-Line - Gone

Not heard this before

One way to get plugs out is to get the engine nice and hot and then try and remove them.
Keep working them a bit at a time and restart engine, and spray wd40 down if you do get them moving a bit

Maybe a job for the summer

Thanks Andy

He is an ex JLR mechanic so i'm sure he's seen it before
Will give it a go later in the year 2015 L494 SDV6 3.0 HSE Dynamic
2006 L320 4.2 Supercharged
2009 BMW X5 M-Sport - Gone
2007 L320 2.7TDV6 SE Buckingham Blue - Gone
2011 Jaguar XFS 3.0V6 Diesel - Gone
2009 (59) L320 Facelift 3.0TDV6 HSE White Wrap - Gone
2008 BMW X5 M-Sport - Gone
2005 Audi A6 3.2V6 Quattro S-Line - Gone

Never had an issue with 4.2/4.4 plugs...

Do they have torque setting?? 2015 L494 SDV6 3.0 HSE Dynamic
2006 L320 4.2 Supercharged
2009 BMW X5 M-Sport - Gone
2007 L320 2.7TDV6 SE Buckingham Blue - Gone
2011 Jaguar XFS 3.0V6 Diesel - Gone
2009 (59) L320 Facelift 3.0TDV6 HSE White Wrap - Gone
2008 BMW X5 M-Sport - Gone
2005 Audi A6 3.2V6 Quattro S-Line - Gone

27Nm

I would spray WD40 on them all and leave it till the weather gets warmer…

Iv done both our 4.2 sc and 4.4 na without issue they were tight but once you crack it off they came out pretty easy. Spraying wd40 down won't do much with the plug sealing ring down there. Hot engine is best way forward.

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Thanks for that youtube link buddy, i notice he says to change them when the engine is cold because it's an aluminium head, not hot as you suggest 2015 L494 SDV6 3.0 HSE Dynamic
2006 L320 4.2 Supercharged
2009 BMW X5 M-Sport - Gone
2007 L320 2.7TDV6 SE Buckingham Blue - Gone
2011 Jaguar XFS 3.0V6 Diesel - Gone
2009 (59) L320 Facelift 3.0TDV6 HSE White Wrap - Gone
2008 BMW X5 M-Sport - Gone
2005 Audi A6 3.2V6 Quattro S-Line - Gone

I think you will get a lot of different opinions about that, personally when I did my 5.0L I removed the plugs with the engine warm and they came out no problem, but replaced them with the engine cold due to different expansion rates between aluminum and steel, my logic was you will get a more accurate torque reading when they are both cold.

Cheers
Col

Aa col says everyone has their preferd method. Yes the heads ally same as motorbikes which iv had for over 40 years so I'm use to changing out spark plugs and always from a warm/hot engine.

Only down side is its so tight in there you do burn a bit of skin