Broken Spark Plug #1

[werd]

So I have a problem with the number one spark plug. The ceramic on the electrode is breaking. Around the beginning of 2016, I put in six champion spark plugs. In September 2016, number one broke. I put this down to a faulty plug.
Replaced with NGK. Now, five months later it has happened again. The ceramic on the electrode has cracked again on number. The gap was huge. About 1.5mm.
Checked the other five champion plugs. They were still good and didn't need adjustment.
So, why is number one plug breaking. Is it just a bad couple of plugs?

[awg]

it suggests either too much heat, or coolant is entering that cylinder

if its too hot, maybe too lean due to a weak injector, vacuum hose situation, or poor coolant flow around that cylinder

I would perform a compression test, which may pick up a head gasket leakage

[rustynuts]

Kinda looks like a sign of detonation maybe in that cylinder. Maybe a blocked injector or more compression on crap fuel in that cylinder.
Try to get your hands on an inferred heat gun and see if there is a difference in your exhaust pipe temperature from port to port.
I doubt two sets of plugs could be at fault with the same symptoms on the same cylinder in a short space of time.

[werd]

Originally Posted by awg

or poor coolant flow around that cylinder

That's interesting. I wonder if the thermastat could be a problem?


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[werd]

Originally Posted by rustynuts

Maybe a blocked injector or more compression on crap fuel in that cylinder.

l fill the car up once a fortnight using woolworths Caltex 91 RON. Then top up with BP 91 RON.
For the last two tanks I've been using BP ultimate 98 RON.
I have some spare injectors so I'll swap number 1 out, but not before I borrow a temp gun and see what's happening.

[bruggz351]

I reckon that 91 is your problem. I've found the 4.0l to be fussy about fuel. JMO.
But I have always run 95 premium and never had problems.
Only times I have, was when I used fuel with ethanol. It farks everything up in an old system.

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