Spark Plug Blown Out?

[Idaho Red Rocket 3]

That sound good. Go for it. Keep us postd plase.

 

[Gerald]

Was there any lasting damage? I used the borescope and the threads look a little rough but intact. As my abilities improve I'll see if I can take some useful pics tomorrow. I'm reluctant to run a thread cleaner down them in case I drop swarf into the chamber though, so after all this talk I'll probably end up doing what Atomsplitter suggested - fit new plugs - if they hold the torque then run it and hope. The pressure gauge fitting screwed in easily and held the pressure, so there is hope......

If you get the right thread chaser, you can put grease between the flutes and it usually holds the shavings, shouldn't be too much material if any.

 

[Bunny Burrell]

Was there any lasting damage? I used the borescope and the threads look a little rough but intact. As my abilities improve I'll see if I can take some useful pics tomorrow. I'm reluctant to run a thread cleaner down them in case I drop swarf into the chamber though, so after all this talk I'll probably end up doing what Atomsplitter suggested - fit new plugs - if they hold the torque then run it and hope. The pressure gauge fitting screwed in easily and held the pressure, so there is hope......

It was fine, it screwed straight back in, tightened them up properly and off he went.
As for your problem, try putting the plug in and see what happens.

 

[Tripps]

If you get the right thread chaser, you can put grease between the flutes and it usually holds the shavings, shouldn't be too much material if any.

It wouldn't take but one piece.

 

[Heidhurtin]

It wouldn't take but one piece.

That's what scares me. There are vids on Notmetube showing guys rethreading the plug hole, and they make kits for this; some take it seriously, some less so, and one buffoon's idea was to run the engine with the plug out to blow the swarf out, but I'm not sure I'd ever be comfortable with it. It'd be a bigger problem with the RIII because of where the plugs are located - really difficult to get access and I'd never be 100% sure I'd got every last piece.

Having said that, I don't have garage and am working on my driveway so removing the head is a job too far. if this plug doesn't hold the torque it may be a case of "here, pass me the threading kit and hold my beer".........

 

[Gerald]

It wouldn't take but one piece.

Agree, but you aren't threading a new hole just removing probably carbon deposit and possibly small flakes of aluminum. Heat and compression should take care of that. If not, you have an excuse to get an up close and personal look inside of the beast.

 

[Heidhurtin]

I also realised the plugs are NGK DPR9EA. The manual says DPR7EA, although some comments on this forum say there's a choice between those and DPR8EA. TheDPR9EA's are colder plugs and could explain why they're a little dark, some minor carbon deposits. I'm starting to wonder what a previous owner did with this engine; PC5 + autotune, colder plugs, Jardines.... hopefully nothing else to discover.