Using an impact driver to remove stuck spark plug?

[shauncr91]

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

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!

 

[shauncr91]

I'd rather use a 3/8 rattle gun on the lowest setting than leverage in this scenario.

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!

 

[shauncr91]

BTW have you tried using a long breaker bar at the end of the extension bar? That would allow you to put some decent amount of manual force than a short ratchet would.

I've never encountered a stuck plug before and as such have no idea how much force they can really take before snapping so I've been trying to avoid this.

Thanks for the replies so far people, hoping the WD40 can loosen it enough to avoid any problems

 

[shauncr91]

Have you tried undoing it with the engine hot? Aluminium has a higher coefficient of thermal expansion than steel.

Not yet, I read that it was a big no-no

 

[shauncr91]

Been busy at work this week going to have another crack at it tomorrow

 

[shauncr91]

And it's out

Kept putting oil down the hole to free it up then took it for a long drive to get the engine hot and it came out hassle free with a breaker bar.

Thanks for the tip on getting it warm guys it worked a treat