Rep Power: 0

Bought 4 NGK spark plugs from Partsource.

Took my car to DIY garage to do transmission fluid change and spark plug replacements.



Took out the spark plugs no problem, was a bit stiff when unscrewing them but no biggie.

With torque wrench set to 14 ft/lb, I tightened until I felt the tight feeling.. but no click.
I wondered why it wasn't clicking but I left 3 of them there but wanted to make sure with the 4th one.

I just kept tightening it until I heard the click... and snap! It broke inside.


The plug's bottom thread was just stuck there, really tight. Had to spend extra $150 for time and labor for the mechanic to pull that out... took 3 hours, probably with some metal brushings in the chamber from grinding various tools to the plug.
Honestly, I'm just happy that it's out now with old plug in.. Car's running fine now (it did had some weird wop-wop for 10-15 seconds from first start but now it's good)


Called this in to the company but only thing they'll do is taking the broken one from me.

I don't know, maybe I've set the torque wrench wrong. because all the other 3 plugs were really tight too- I did set it way below the 20 ft/lb mark which was the lowest number it had... could've been worse but yeah.
TIL, never over tighten spark plugs.

 
Rep Power: 221

Never used a torque wrench on spark plugs
Just run them down and then snug them. And if the torque wrench doesn't go low enough for the torque you need don't use it, you won't be anywhere close to accurate

 
Rep Power: 0

Was my first time so I wanted to follow by the guideline... I'll just snug them next time

 
Rep Power: 511

Yeah, the torque spec on spark plugs is 13-15 ft-lb. I would never use my 20-150 ft-lb torque wrench on those. I always opted for my 25-250 in-lb torque wrench set to 165 in-lb (comes out to 13.75 ft-lb) and have had zero problems.