Spark Plug blown

[swellybro]

Hi,

Had to pick my wife up yesterday as we have had a little problem with her Clio Sport 172 (I think it will be the end of me ).

Apparently there was a loud clunk and then the engine was making a loud tapping banging noise - luckily she pulled over asap.

Towed the car back home last night and I have been able to have a look at it today. It appears a spark plug has worked its way loose out of the 1st chamber, it has completely knackered the HT lead but the spark plug doesn't look that bad apart from the gap is squashed and the thread on the plug looks ok.

If it has destroyed the thread in the engine, has anyone else on here tried to helicoil a new thread?

What size helicoil is needed? would this be ok? http://www.ebay.co.uk/itm/Draper-He...t=UK_Hand_Tools_Equipment&hash=item1e6a4491cd

I changed the plugs over a year ago so I'm feeling slighlty responsible.

Any advice is greatly appreciated

Thanks

Richard

 

[swellybro]

Just trying to find out what other people would do..? I've got the spark plug out, but not sure what condition the thread is in. Could the spark plug have just come unscrewed, in which case would it be okay to just put a new plug in, or would you helicoil, just to be on the safe side? Thanks, Richard.

 

[Sash]

Im no means an expert - try Fred or Sideways Danny - but if it's worked its way loose, and there appears to be no head damage try a new set of leads and plugs and try again...

 

[MonkeyKnifeFight]

I had this exact problem!! i had the thread helicoil'd, replaced the ht lead and spark plug. Had the car back on the road within 2 days costing me little over 100 squid. Fingers crossed most if not all the metal was blown out rather than dropping into the chamber.

 

[swellybro]

Hi,

Thanks for the replies, problem is it's very hard to know if there is any thread damage.

I think I'm talking myself into helicoil, but I'd rather not.

Hmm

Thanks

Rich

 

[MonkeyKnifeFight]

The chance of the thread being ok is very slim i would say. The plug would have wobbled loose then under pressure taken a portion of thread with it, i cant see it working itself completely loose then firing itself through the ht lead. But im just going by the state of my ht it was destroyed and the end of the plug was lodged in the ht lead.

 

[swellybro]

Exactly what's happened to mine, ht lead destroyed. Think it's easy to forget the enormous pressure a spark plug is placed under.

I think helicoil is the best option tbh just trying to avoid it.

Any idea what size the helicoil is?

Thanks

Rich

 

[MonkeyKnifeFight]

I agree!! if the inlet manifold wasnt covering the sparkplugs i bet it would have made a mess of the bonnet!! but in the same breath if the inlet manifold didnt cover the sparkplugs it would be a hell of alot easier to check if the plugs are tight enough lol.

Im afraid i cant help other than share my experience. Good luck with sorting it out.

 

[Dan519]

I'd use an insert rather than a helicoil. Definitely worth just trying a new plug to see if the original thread is ok first though

 

[Cooksport]

However, if the end of the plug looks squashed like you said. I would
Investigate further.

Could have dropped a valve, would be unlikely that this would cause the plug to push out. But I would certainly look into it. Usually a plug coming out would be a misfire, not a loud tapping noise you described.

 

[Cooksport]

If im talking out my ass though... Do what Danny said....

 

[MicKPM]

I'd use an insert rather than a helicoil. Definitely worth just trying a new plug to see if the original thread is ok first though

Another "as per Danny said"... 100% use a timesert rather than a heli-coil. Okay, it means taking the head off but they dont un-wind like helicoils and if you choose to do the oppersite be sure to tell anyone you let service the car know it has one so they aren't tripped up when they remove the plug and take the wire out with it.

 

[LIL B]

Had a bike sump coiled once, the stupid b******s.

insert is a must.

 

[Martin_172]

heli-coil is cheaper but not quite ideal. however ive known 2 people who have used them on 172's and got away fine with it!

 

[not normal dan]

I had exactly the same back in the summer on me old 172, thread on head was fine for me so new set of plugs an leads sorted it for me, as said though go for an insert over a helicoil.