Any foreign object bouncing on top of a piston can cause lots of damage.....I’ve never heard of an iridium plug failing though!
I have seen a side electrode come off and be stamped into the piston crown (Ford CVH) and the mess was considerable.
John
I’ll edit.....it is possible for an incorrect heat range plug to melt in extreme conditions.
Yikes!, i could take a plug out to check but looks tricky to get it out. Is there a standard torque setting when putting it back in? It's that zetec with exhaust problem i posted about
Nothing to be particularly bothered about but you will need a slim 3/8” drive spark plug socket with an extension. I’m fortunate to have a magnetic socket that makes removing and refitting plugs a breeze.
You have to be very careful removing the coil packs on top of the plugs, lift them off square after turning them a fraction.
Mighty expensive things, iridium plugs but they do last ages. I don’t use a torque wrench because you can feel the washer compressing and then a slight twist more is enough.
John
Thanks again john, i take it the engine would just misfire if worn plugs rather than damage to engine?
Im trying to get things sorted before tier 4 reaches us
Yes, that’s about right....it isn’t unknown for a dud plug to take out the coil pack though which is why you shouldn’t crank the engine over without the plugs being grounded.
John
I use an old piece of servo hose from a 1976 Victor for that. I use it to both remove the plugs and to replace them. I only use the socket to slacken and to tighten the plugs, the rest is done with the servo hose as it gets a good enough grip to do the rest.