This.

The piston hitting the plug directly is all but impossible, the plug is fixed, the piston stroke is fixed.

The only thing in the cylinder which can contact a piston is one or more of the valves.

Or a foreign object that made it's way into the cylinder somehow, like a bolt dropped in there while the sparkplug was out.

Not a chance that the sparkplug "exploded" on it's own.

Something else was loose in the cylinder and got between the sparkplug and the piston top.

 

OK, I think the shop is full of crap but we need to move forward and see the extent of the damage. Use a bore scope to inspect the cylinders / valves etc. through the spark plug hole. You should be able to see valve impact marks on the piston tops of all the cylinders on that bank if a cam is out of time.

Personally I'm going with FOD got down the plug hole and then banged around. Hard to say if they didn't drop the plug and shattered the core without realizing it, then troubleshot the cylinder miss until the plug fell apart and got worse. Or somehow a chunk of metal got down there. Also if your bore scope results only show valve to piston damage in one cylinder then 'something' held the valve open and the piston whacked it, most likely bending that valve.

That's a ton of damage and I suspect the piston top is pretty beat up as well. Notice this picture evidence of my dad's accidental 'losing' a 5/16" carb mounting nut on a Chevy 350 in his boat...



So, moving forward to troubleshoot. Inspect each bore and if they look clear, have them do a compression check on all 8 bores. That'll show if you have a bent valve and won't cause further damage. If you have low compression it's coming apart. Note which ones are low so they can concentrate on the problem bores. If the compression is good the only specter you have is rod bearing damage and it's difficult to troubleshoot without taking it apart. I'd consider putting the plugs in and firing it up. You'll hear the loose bearing if it's damaged.

 

 

Are you attempting to say that the OP experienced a spark plug failure and not reassembly error on the part of the Technician?

 

Stuart I always get a chuckle out of those "Zero Emission" claims for the elec. cars--or for anything elec. for that matter. They never consider the plants producing the elec. Even if provided by solar or wind there is a huge MFN footprint in production of the same. LOL

 

Oh they can explode.... Its rare but it can happen. If spark plugs are faulty from factory, they can work for even a year before they explode. Trust me i have seen this happen.. Adnt there wil be pieces all over the cylinder. You just have to hope that pistons and other bits are fine... When mine exploded, it broke the coil pack at the same time..

 

,I would say it's more likely that top of the piston broke off and hit the plug or a foreign object unless we are talking about some Chinese clones for spark plugs

 

I'm not sure how a plug, in itself, can explode? I have witnessed plugs blow out like projectiles due to weak aluminum threads in the heads.
Is this scenario, what is being discussed?

 

Guys you do realize this is a 5 year old thread. I have seen the plugs blown out of the head, as stated due to weak or damaged threads, and I have seen the porcelain centers blown out. from crappy manufacturing, and not withstanding the pressures of combustion. I have been working on everything from 14,000 RPM motorcycles to Ferraris, Lamborghini's, Maserati's, Jags, Hot Rods, and 10,000 HP dragsters, and everything in between over the last 50+ years. Spark Plugs Don't Explode! Spark plugs get damaged by "Something" introduced into the Cylinder! Whether that is something dropped into the plug hole, or something dropped into the intake tract / carburetor, that causes mechanical damage, or by improper valve timing, which causes bent, and broken valves. Which can damage the end of the plug, such as seen in the pics at the beginning of this thread. But the Spark Plug itself Exploding is a load of BS. It simply doesn't happen, and if someone tells you it does. They are for whatever reason, trying to cover up the real cause of the damage.

Jack

 

So, singaporecat, 5 years later, what was the result?

 

After some negotiation they accepted the responsibility, the car was due to be exported to the UK 6 weeks before the incident, this still happened, as a 'non-runner' though, which saved me some import tax as the value was reduced. The shop ordered me a brand new engine from Germany which was shipped to me UK Jag specialist that fitted it all for me. Its been working fine ever since back home in UK.