Focus 2.0 Duratec (2010) Engine Knocking Noise

[Hellonpluto]

Hi,

This morning my focus started to hesitate and there was a popping sound coming from the engine which felt like a mis-fire.  I was very nearly home when it started.

Upon inspection of the second spark plug from the left side of the engine the electrode was completely missing.  I've changed the plug with a spare one.

Now, the engine is making a loud knocking / tapping sound.  Anyone hazard a guess what damage the electrode may have done?

Link to video of the noise on youtube: 

thanks in advance.

[KenM]

You might as well pull the head off and have a look if you can, there has probably been a problem with that cylinder for that to happen.

[unofix]

Is the coolant level normal ?

If you have a head gasket leak then you may have had a partial hydrolock in that cylinder causing it to blow the centre out of the spark plug.