Engine Problems. Help Needed

[RMK87]

Hi All,

Was driving along and car starts juddering pretty violently. It still drives but engine shakes pretty bad. Get it to a garage in the morning and cylinder 3 is misfiring. Replace the coil lead and still misfiring. Pull the spark plug out and it was broken!

Mechanic said looks like piston hit the spark plug. Cant do that kinda job here for you. What am I looking at?

Timing belt/water pump, coolant, oil and spark plugs are all less than a month old. 

[flashp]

I'm in no way an expert, but I might guess that this failure could be related to the recent work you had done. Re-examine all the work that was done. What condition is the timing belt in?
Slipped maybe??

Just a thought.

[pudding]

The piston can't hit the spark plug unless the wrong kind is used (sits too far into the cylinder, but you'd know straight away!).   More likely the electrode got bent if someone dropped a plug on the floor, or it melted away due to detonation.  Need to see a pic really, and / or confirmation they are OEM plugs?