Anybody ever heard of this happening.

My 2007 XKR (60,000m) is in the workshop here in Singapore. It’s coming up to its 10th birthday and as such it’s 10 year license will expire and it’s going to be deregistered and I’m exporting it back home to UK to keep my XJR company.
It had a small oil leak at last service and while that was being fixed I used the opportunity to replace a bunch of items (water pump, timing belts, tensioners, chain etc). All that was done by the independent specialist here and when they fired it up again the spark plug (all new) exploded and has destroyed the piston, valves and god knows what else) of the first cylinder. I’m looking at a replacement engine or rebuild (if possible). I’m in shock, it went in to fix an oil leak and do some sensible engine preventative maintenance and it’s now F$&/@D ... has anyone heard of exploding plugs destroying a cylinder before ???

The plug from cylinder 1

 

Wow , interesting as it looks like maybe the piston hit the plug. I don't understand how the plug blew out.

 

I never heard about spark plug exploding, but I did hear of piston hitting plugs. This could happen if you use wrong plugs or severely over-tighten your plugs.

I think the shop destroyed the engine and now BSing you. Don't let them not take responsibility for this problem. This is not normal, this doesn't happen by accident, this is not related to normal wear and tear.

However, pistons are very durable and your engine could have survived this mishap. Boroscope examination could show what happened, possibly allowing to fix this with only heads off.

 

this+1

 

I'm with SinF, I don't buy the exploding spark plug story. This sounds like mechanic error.

 

I don't understand the need to replace the timing chains and tensioners on the 4.2 litre. There is no 'timing belt' on any AJ-V8.

Spark plugs that appear such as that have suffered from an impact. If indeed you did have the timing chains replaced, the most likely cause is incorrect cam timing during reassembly.

It may be best to return the vehicle to the UK for repair if the competency of the shop where it is now is in question.

 

Agree with all above! I can think of no instance where a spark plug was capable of "exploding". They are a simple electric devices that provides an air gap that sparks jump across. So it would be physically impossible for a spark plug to explode.

Bore scope photos are in order to see what the top of piston looks like to better understand what happened.

Human error is the most likely answer which wouuld mean the shop should be responsible for this very sad result.

 

This engine has no timing belts at all, nor are the timing chains or tensioners routine maintenance items as they were on the 4.0 engines.

My guess is your mechanic misassembled the engine causing the piston top to hit the spark plug.

 

Or the piston impacting and breaking a valve that bounced around inside the cylinder and destroyed the spark plug.

If that is the case, the engine should not be rotated until the timing is inspected.

 

I'm in agreement, it's a mechanic error. Piston definitely hit the plug!

 

Spark plugs don't explode and that is probably one of the most insulting and poorly proven excuses to cover up crap work. Additionally, unless the spark plug is way too long, as in, at least 5mm too long, there's no way a dished top piston is going to hit a plug in a pent roof combustion chamber. That's like saying the rear tires wear out because they rub against the drive shaft. It's just nonsense and physically impossible. Furthermore, the damage to the plug is from multiple impacts, not an "explosion."

My hot take based on seeing what a jumped timing belt on a Honda engine does: Assuming those are the right plugs, they mistimed it when they put the timing chain in. This one is on the shop, and they owe you an engine.

 

This is most likely.

Also, I sure hope the shop didn't tell you that the spark plug exploded and caused the damage to the cylinder. High school shop students know better than that.

 

I had a Ford Explorer that I took in to have the plugs changed. They had never been changed before, so they were still original. The car had no power when I brought it in, but it ran smooth. The shop calls me and says I need a new engine. I was floored. I asked if it ran, they said yes, so I picked it up and took it home. It ran extremely rough. This made no sense to me, so I took it to a different shop and asked them to troubleshoot. They told me that they discovered 4 plugs looked new, two plugs were original, and one of the original plugs was cracked. So obviously the original mechanic tried to change all 6 plugs, was successful on 4 and broke 1 of the remaining 2. But rather than tell me this they said I needed a new engine! Got those last two plugs changed and the car ran another 100,000 miles. I really hate dishonest/incompetent mechanics.

 

DO NOT let this shop do any further work on this engine until the cause of the damage is found. I hope they used the correct tools to hold the camshafts in place during replacement of the primary and secondary timing chains.

They should rotate the engine in a clock direction when viewed from the front of the vehicle BY HAND with the cam covers removed to see if the camshafts are correctly timed.

 

You have a conundrum on your hands that will require some clever thinking.
If the mechanic lacks the competency to time an engine, you dont want him rebuilding it. Or even putting another engine in. Which he wont be able to come out of pocket for.
It is a lawsuit you can easily win- because he made the error of blaming a massive company whose experts can easily be deposed to provide irrefutable testimony that its an impossibility for the plug to do that.

Perhaps awareness of all of this might encourage that shop to find a suitable answer.

 

Here is the NGK head offices in Malaysia.
Reach out to them, let them know a garage has insisted one of their NEW plugs exploded causing catastrophic failure. See what they say.
Home

 

This is 2017, where are the camless engines? Why do we still have to deal with these rolling crowbars that have no ability to self-calibrate?

 

If I may take this opportunity to point out something pertinent.
This is a great example of why old rules of preventative maintenance are counterproductive nowadays.
You are better off waiting for a part to break than proactively replacing it. Because chances are the new part and the new labor is no where near as good as the part you are taking off. Because workers have a gun held to their heads these days to produce, and it leads to inferior results.

 

I remember reading this last year. Apparently, as of last November, it's almost ready

The Camless Engine of the Future Is Almost Ready for the Real World

 

But will an internal combustion engine, regardless of cost and fuel economy, survive in the face of electric motors with zero emissions? Certain death by politicians.