LR3 Spark Plug Pics

[Mack73]

I call BS. The article says that installers are overtorqing the plugs causing the threads to mechanically fail. Right, so install plugs that will gall to the heads because some nimrod runs them in with an impact wrench.

****** does not know how to install a spark plug?

Suggestion: use anti-sieze and don't let that guy install your plugs.

How about straight from NGK: https://www.ngksparkplugs.com/about-ngk/spark-plug-101/5-things-you-should-know-about-spark-plugs

1. Anti-seize
NGK spark plugs feature what is known as trivalent plating. This silver-or-chrome colored finish on the threads is designed to provide corrosion resistance against moisture and chemicals. The coating also acts as a release agent during spark plug removal. NGK spark plugs are installed at the factory dry, without the use of anti-seize. NGK tech support has received a number of tech calls from installers who have over-tightened spark plugs because of the use of anti-seize. Anti-seize compound can act as a lubricant altering torque values up to 20 percent, increasing the risk of spark plug thread breakage.

 

[DiscoDavis]

That is definitely interesting, but I have never had an issue using anti-seize on spark plugs. I've also never used a torque wrench, so I could see how anti-seize could throw off torque value. I have, however, fixed a handful of cylinder heads on Land Rovers where the spark plug pulled the threads out of the head and they did not have anti-seize.

Do you just go a bit past hand tightened? Always wondered about the specific torque value. Mine loosened up after the summer months.

 

[DiscoDavis]

I call BS. The article says that installers are overtorqing the plugs causing the threads to mechanically fail. Right, so install plugs that will gall to the heads because some nimrod runs them in with an impact wrench.

****** does not know how to install a spark plug?

Suggestion: use anti-sieze and don't let that guy install your plugs.

FYI this was straight from NGK, just used some NL hosting site. PDF copy was buried in one of the build threads.

 

[jymmiejamz]

Do you just go a bit past hand tightened? Always wondered about the specific torque value. Mine loosened up after the summer months.

It is very hard to explain to someone how tight to make things, it is something that is learned over time. I have two apprentices at work and this is one of the most difficult things to teach. I tighten them a little past where I feel the sealing washer start to crush. Anti-seize helps to prevent fasteners from backing off as well as keeping them from seizing in place.

Just to be clear, you did not use anti-seize, but did use a torque wrench, and they loosened?