Really stuck glow plugs and how I managed to remove them without breaking any! Part 2 

Idling the engine while removing a glow plug could be a very useful tip. For anyone (like me) who's trying to learn about this job as much as possible before trying it I have a suggestion. Get hold of some old glow plugs (A friendly garage might help with some they're just going to bin anyway), clamp them well in a vice and practice snapping them with an ordinary socket wrench and/or torque wrench. The idea is just to get a feel for how much torque is needed and to see where and how they break. Another tip (from working on old wooden doors) is the tap-n-twist method used to remove those awful old screws with just a worn and rusty slot to apply torque to. Using a hammer, tap rapidly the end of your screwdriver as you apply a firm twist anticlockwise. The "rebound" to each tap actually pushes the screw back up, aiding your unscrewing in the process. Some have applied this method to glow plugs. I'm not sure it works in exactly the same way but it seems to help - perhaps by breaking up the seal between the plug and engine around the threaded part or the shaft between the thread and the exposed tungsten core which sits inside the cylinder. Be careful not to strike too hard or onto your best ratchet though - might damage the mechanism. Probably best just to use a simple wrench or just the extension.

John is wrong. This is an awesome video. I have the same problem and this gives me insight. You can hear the wrench jerking as it turns and it is brilliant to run the engine so the compression in the cylinder is pushing on the plug.

Braking = Slowing down or stopping with brakes..... Breaking is the word you want ;-)

How can it turn so many times? Is the ratchet slipping?

How long is that thred.?

Not a very good video, sorry.