Over Torqued Spark Pkugs

Hi Everyone,

Sorry for the dumb question but I finally got around to changing the spark plugs on our Tacoma.

I used a torque wrench torqued to 14 ft-lbs. (in case my Harbour Freight torque wrench is off) and I’m wondering what technically is over torqued? For example if the spark plug was torqued to 16 or 17 ft-lbs is that very bad (the range is 13-15 ft-lbs.)?

Thank you in advance.

 

Common for torque wrenches to have a +/- accuracy. I think Tekton and a lot of other brands are 4%. 16 or 17 vs 15 ft-lbs isn't a big deal.

Be sure to store your torque wrench according to the manufacturer though. Some types specifically require you to store them at their lowest setting. A lot of people dont do this, which worsens the accuracy over time.

 

A couple ft/lbs over isn't gona hurt anything, better to be a bit too tight than not tight enough.

 

Usually hand tighten, then 1 ugga then should be fine

 

Thank you everyone!

 

That's pretty much what I have been doing for more than 50 years. Hasn't failed me yet.

In fact the only thing I use a torque wrench on is lug nuts, so they'll be equally tight. Just in case I have wheels that might be prone to warp.

 

I always torque mine with a baby 1/4 ratchet till my one hand cant turn it anymore. Hasn't failed me or bit me in the ass yet!

 

1GR engine is 15 ft/lbs
2TR is 13 Ft/lbs

Thankfully Toyota gave us plenty of threads in the heads of both engines.
You’ll likely crack the porcelain from over tightening way before you do any other damage. I’m quite sure I get mine “too tight”. I never used a torque wrench yet.
I might the next time, just see. If nothing else just to check my “by feel” like I’ve always done. So far, I’ve been ok.

Ford modular engines on the other hand.
They make me super nervous, there’s about 2 whole reads that hold the plug in.
Too tight and it’s game over. Too loose and they blow out. Literally blow clean out of the head.

 

I worked with a guy in St. Louis that drove an older F-150. One day, he was late to work because he said he was on his way and his engine blew out a spark plug. He lived out in the country and was only a little late.
At my current place of employment, people will miss the entire day for a flat tire....

 

And if you use anti seize, you'll have no idea what you're torqueing them to.

 

While that is true. Denso says , if used, use sparingly and reduce torque by 30%.
If I use anti-seize on automotive plugs, I get them good and snug. If it feels snug, it’s probably “more snug”.

I’ve actually stopped using it lately, most manufacturers don’t recommend it.
And the major of plugs use a special metal coating. I will still use it on older flat black tapered seat plugs.

 

I just use a impact to install plugs Ugga duggaaa

 

Nice troll.
We shall see where this goes from here.

 

Of the last 3 sets of plugs I did, 2 were backing out coming loose, caused muck on the head threads. I tightened the new ones, they didn’t feel seated properly. So I put my T bar on it, repeated tightened loosened, every tightening it went in a little further until it finally seated.

I’m with the uga duga plan. I don’t care what the Toyota manual says, I’m just not comfortable with 15 ft lb on my plugs. You could probably achieve that with a finger ratchet.

 

Yeah if you look at the little box they often show getting them hand tight, than add a 1/2 to 3/4 a turn....as long as you use anti seize and are somewhat close if a little extra snug you should be fine.

I've done at least 15 sets of spark plugs in my life from my vehicle, wife's vehicle, parents, etc. The only ones I ever had a hard time with was on some plugs I took out of a vehicle I had bought second hand and the previous owner said he never used anti-seize on would had sized so bad I had to stick a torch down in the hole, then put in an easy out, tap with a hammer and throw a breaker bar on as fast as I could to keep it from cooling (if you can't tell the porcelain had already separated from the threads)....it was on an old jeep I had, that thing was the biggest PITB I ever owned.‍♂️

 

Were the ones that were coming out torqued with a torque wrench?
I’m not sure what you’re saying? Who installed the plug the before, and how did they install them?

I have yet to use a torque wrench on any plug. But I’m not against it either.
I mostly use my torque wrench on smaller bolts and plastic parts. Like intakes and such.

 

Those plugs were all factory installed in Nissan engines, no anti seize.

 

My dirty plugs at 171,000 kms.

 

Actually, it's 3 threads and only on the very early modular motors. (1997 - 1999 if I remember correctly.) The next generation of modular motor (2006 as I recall) fixed that problem with a new (equally stupid) head design that included a new spark plug design with a super long reach. This long reach was to poke through a super long hole bored in the head leading to the spark plugs - which of course carboned up over time. This lead to a new problem - plugs that wouldn't come out.

 

So about 106K miles. Obviously way too long between plug changes, even if they are iridiums. Thanks for the pics!