Stuck Spark Plug on renault K4J 1.4 engine

Stuck Spark Plug on renault K4J 1.4 engine

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Discussion

AlVal

Original Poster:

1,883 posts

263 months

Thursday 19th May 2011
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Hi, I went to replace spark plugs recently (first time during my ownership, car at 36000 miles) and I noticed as I worked through the plugs from left to right (car is an 05 megane II hatch) there seemed to be more and more corrosion in and around each chamber. the 3rd plug came out with some struggle, but there was too much corrosion around the 4th spark plug chamber, I stopped trying before I ended up completely rounding the head off the plug, and decided to leave it to a mechanic. My local friendly mechanic, who's very trustworthy, and an excellent chap all around (godsend given my previous experience with mechanics) didn't want to touch it, as he said it could get very expensive if it goes wrong, i.e 800-900 quid if the head has to come off etc because that would mean timing belt etc etc, shame as I've literally only just had timing belt/water pump/etc done.

Are there any tricks to getting a spark plug that's stuck out? and how can I remove any existing corrosion around the top of the head and in the spark plug chambers to halt the corrosion in its tracks and stop it spreading further? I replaced the four ignition pencil coils sitting in the chambers on top of the plugs as I think at least some of them looked badly burnt from whatever corrosion had been happening in and around the last plug or two.

any advice really appreciated. I'm based near Luton, so if theres a garage anyone knows of that specifically specialises in this kind of work (maybe its just something my mechanic doesn't want to tackle as he's not extensively experienced at it?) a reccommendation of such would be appreciated

thanks!

Steve_D

13,737 posts

257 months

Thursday 19th May 2011
quotequote all
As has been said a dangerous game.
I would put some WD40 or diesel in the plug cavity and leave it a few days then try again with the engine hot.
You may also want to try tightening the plug first as this may serve to break the seal the corrosion has created. All the time you are trying to remove it keep the area soaked in the WD40 or diesel.

In my area we have a mobile thread guy who specialises in removing broken bolts etc and can helicoil plug holes without removing the head. No doubt the same service exists near you.

Steve

wildoliver

8,766 posts

215 months

Thursday 19th May 2011
quotequote all
Plus gas for a few days. Before and after driving. Before removing the plug a good hard blast to really get some heat in there and final plus gas applying.

Break head off plug (do or die at this point) good wallop with hammer on the body of plug to free the threads. Impact socket and wind out. It will come out, the question is whether it takes the threads with it.

Pumaracing

2,089 posts

206 months

Thursday 19th May 2011
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As the coefficient of expansion of steel is lower than aluminium, plugs should become a bit looser at high temperature so try removing it with the engine hot. Tool techniques for dealing with stuck components are on my website.

DrDeAtH

3,586 posts

231 months

Thursday 19th May 2011
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use PlusGas instead of WD40. It will penetrate the thread, WD wont....

AlVal

Original Poster:

1,883 posts

263 months

Friday 20th May 2011
quotequote all
thanks very much guys. I might give a gentle go with the plusgas and see if there's any budge.

another bad thing I'm doing is using one of those nasty cheap spark plug removal tools made out of rubbish metal, I doubt this is helping at all, which is why I didnt want to use it any more and round the head off the plug - can anyone advise what the best brand of tool for removing the spark plugs is?

Pumaracing

2,089 posts

206 months

Friday 20th May 2011
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Any decent make of 6 point plug socket will be fine and far better than either those thin tube tommy bar things you get in car tool kits or even a 12 point socket.

If anyone can explain to me how penetrating oil can possibly get into a spark plug thread when the plug has a crushable metal washer above the thread designed to seal against the hundreds of psi pressure in a firing combustion chamber I await elucidation with bated breath. Maybe if the plug can be budged even a tiny bit first then perhaps.

The ideal thing to do is try and shock the plug loose first. That means having some sort of hollow metal bar or deep reach socket that fits over the porcelain insulator and bears on the solid metal body of the plug below that. Depending on the plug design this may or may not be possible. I'd just knock something suitable up on the lathe but few people have that facility. A few good belts on that should help greatly as with most stuck fasteners.

http://www.pumaracing.co.uk/ToolUse.htm

Bugeyeandy

10,774 posts

196 months

Friday 20th May 2011
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Pumaracing - I don't think it does get into the threads to begin with, more likely it seeps into the corrosion at the mating surfaces and dissolves bits of that.

Once you've got rid of that bit of friction, loosening bit by bit with a spray of plus gas or freeway will allow it to seep into the threads. It does work a lot of the time, certainly doesn't do any harm so long as you don't let the car try to start with a load of it pooling on top of the piston biglaugh

I know a lot of mechanics scoff at the use of such fluids (as they are seen as some sort of snake oil) but we use it a fair bit at work and it really does work.

blitzracing

6,387 posts

219 months

Friday 20th May 2011
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Just as a thought about the corrosion, the old Renault Megan Scenic we have has corrosion around the plugs because the rubber seal that runs along the back of the bonnet allows water to run straight into the top of the engine when it collects in the drip tray along the front bulkhead. I know you have a different model but it could be the same design flaw? All it needed was plenty of silicon rubber to stop the leak.

AlVal

Original Poster:

1,883 posts

263 months

Sunday 22nd May 2011
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thanks lots guys,

pumaracing's technique (hot engine, downward shock tap applied to metal body of plug, avoiding insulator) to help crack combined with some plusgas, which definitely helped, and really does seem to "dissolve" rusty bits into brown mushy liquid quickly, worked a treat.

my main concern was , and is, what effect the bits of filth that will have fallen into the hole in the head for the spark plug after spark plug removal will have - is this dirt/few millilitres of plusgas falling into the engine via the spark plug hole likely to cause any long term damage? the engine did start ok thankfully, and is running much smoother.

I can think of no good way to properly clean out all the corrosion and dirt from the recessed chambers in the head which hold the pencil coils and spark plugs, can this only be tackled with the head removed?

paintman

7,669 posts

189 months

Sunday 22nd May 2011
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Henry type hoover with a thin tube taped into the crevice tool nozzle is great for getting into awkward areas.
Just don't get caught by the OHeek & be sure to clean any oil off. (I have one specifically for garage usecool)