Hello you lot

in August I had a misfire no engine light 

the 2nd plug along from timing belt had broken

i changed all 4 and all was fine until Thursday just gone 

cruising along the A2 doing 70 suddenly car started to slow and engine light came on I managed to get off motorway and called RAC he plugged his machine in and code came up saying plug number 2 had a misfire 

it was the same plug as before and had snapped in half ????

he replaced all four plugs and all is good again

he also said he has no idea why a plug would break like that and maybe I had been unlucky 

Has anybody got a view on this and what might have caused it to break ? 

Thanks for reading 

 

unless it was over tightened I can't see a reason why a spark plug would break to be honest it could be it was overtightened they only need to go in hand tight then a quarter turn with a ratchet maybe someone else has another theory

12 minutes ago, artscot79 said:

unless it was over tightened I can't see a reason why a spark plug would break to be honest it could be it was overtightened they only need to go in hand tight then a quarter turn with a ratchet maybe someone else has another theory

That's exactly what the RAC man said but he didn't think they were too tight ? 

I am hoping I've just been unlucky 

 

Define snapped in half? did the metal body snap, leaving the threaded portion in the head or was it the electrode end with damage. 

My guess is yo could have a fuelling/cooling problem to that cylinder. The Sparkplug could be getting too hot.  

Yes it was a clean break at the base of the ceramic bit 

so the plug was in 2 pieces

on the first plug it was the top that had broken leaving the threaded bit and ceramic case

Is number 2 plug difficult to access at all?  Needs to be dropped in rather than placed?  Cross-threaded so there's a slight lateral force on it when tightening?

Tbh I'd be wondering about the coil pack, putting too much voltage through that plug.  Just an idea though as I haven't seen it happen twice in a row either!

3 hours ago, TomsFocus said:

Is number 2 plug difficult to access at all?  Needs to be dropped in rather than placed?  Cross-threaded so there's a slight lateral force on it when tightening?

Tbh I'd be wondering about the coil pack, putting too much voltage through that plug.  Just an idea though as I haven't seen it happen twice in a row either!

Coil pack is a good shout. It might be worth replacing it anyway as a precaution.

If the plug goes a 3rd time you could end up with debris in the cylinder, not a pleasant thought.

Thanks guys 

i might just have a look at coil pack

 

the coil pack couldn't put out enough current or heat to snap a plug to be honest ide change the plug apply a thin smear of copper grease to the thread on the plug and carefully fit ensuring it doesn't tighten if you're changing a coil pack you need to change the leads easy way to spend £100

But be careful with the torx screws, they can be hard to remove. Even my garage could not remove them!

Thanks again guys

The RAC man changed the plugs and put stuff round the threads etc etc

he was very careful putting plugs in and tightening them 

he was very good even checked for anything odd before he put plugs in and said there was nothing obvious and it all looked clean and tidy

Sorry to revive an old thread but I have this exact problem changed plugs and coil on cylinder 2 on 58 plate 1.8 zetec and just done it again, did you fix it?