Using an impact driver to remove stuck spark plug?

Soldato
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I've got a stuck spark plug in cylinder 1 on my Fiesta ST and I really want to get it changed as I've done 3 out of 4 plugs :mad:

At the moment I've got it soaking in penetrating fluid which I'm going to keep doing daily for a week or so but if this doesn't free it up, would using an impact driver VERY carefully be safe to use? This was suggested by a friend that I use it with just minor knocks but I'm worried it could damage the head with the downward force.... the Duratec has an aluminium head if that makes much difference.

Just so people don't get confused, I'm talking about using one of these with an extension, not a rattle gun.

Thanks!
 
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Soldato
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26 Jun 2011
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4,902
Definitely avoiding leverage where possible, quite frankly I'm not in a position where I can have the car off the road with the head off because I snapped a plug or stripped the thread!

In this case off it goes to a shop. Pull all the old sparks back in and tell the shop that you want them changing. No other details.
 
Soldato
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Try leverage on it I would, and do it while the engine is HOT. Have changed many plugs in my time, plenty of which have been stupidly tight. Leverage always works plus a hot engine.

Guaranteed to come back with 3 new plugs in this case.

Mark them with a blob of paint and request the old parts back.

Had a regular customer do this where I used to work, every time there was a dab of paint on the oil filter and plugs!
 
Soldato
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Drunken badger punching
NO NO NO. You need to feel the thread moving, not annihilate it.

Have you tried doing it with the engine at different temperatures?

Fingers crossed it's not tight due to being cross threaded by a retard.
 
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Caporegime
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Fingers crossed it's not tight due to being cross threaded by a retard.

I had a Fiesta a few years ago and one of the spark plugs rusted itself into the cylinder head. Fiestas had a problem with the front washer jets leaking into the spark plug hole and the pool of water would weld the plug into the head. Was a head off job on mine, then they drilled it out and fitted a new thread insert. Hopefully this isn't the op's problem as it cost £600.
 
Soldato
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17 Mar 2004
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I had a Fiesta a few years ago and one of the spark plugs rusted itself into the cylinder head. Fiestas had a problem with the front washer jets leaking into the spark plug hole and the pool of water would weld the plug into the head. Was a head off job on mine, then they drilled it out and fitted a new thread insert. Hopefully this isn't the op's problem as it cost £600.

well no as he has already stipulated that it has an alloy head ;)
 
Associate
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8 Dec 2006
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Bromley
Gentle impacts is much better than leverage in this instance. Especially when it's going to involve a deep socket with an extension on it.

I still stand by leverage using quarter turn method all your looking to do is just break the seal. people seem to think leverage is going in full force like a Neanderthal. That's not the case if its done properly by a competent person.
 

Xez

Xez

Associate
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24 Jun 2005
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Lincolnshire
I still stand by leverage using quarter turn method all your looking to do is just break the seal. people seem to think leverage is going in full force like a Neanderthal. That's not the case if its done properly by a competent person.

A bit of heat and a t-bar does wonders for this kind of thing!
 
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