Unless you are using a 1/2" impact gun and holding the trigger, good and tight will not strip the head. Just turn and tighten til it stops turning, smack it a bit with your palm to confirm it does not move and you are set. Otherwise spec could be 13 ft-lb - 18 ft-lb. Don't make things hard, that is what I try to do (and tend to fail at).

(This ain't no Domestic)

 

Otherwise spec could be 13 ft-lb - 18 ft-lb.

I torqued it to 18 ft. lbs, which is what is in the Toyota repair manual, but based on how it felt, I would say 13 ft lbs is fine.

 

I'll probably change my spark plugs with a year or so. Last time I did them I had the iridiums and I did not use a torque wrench. I did not see a torque spec on the plugs themselves, does the torque spec get set via the plugs or what Toyota specifies ?

Last time I did them, I hand tightened them, then probably tightened them another full turn or so and made them tight. I've read that if you overtighten the plugs you can strip the threads since the block is aluminum.

I did not use a breaker bar or anything, just a standard rachet wrench. The threads likely did not get stripped b/c of tightening without a torque wrench did they ? I probably will use a torque wrench in the future, but something I never thought about before and now thinking about the last time I changed them.

I just happened to change the plugs on my Corolla. The torque is 18 ft. lbs. One of my old plugs was stripped, and so was the hole into which it threads. I had to clean up the threads with a tap (same size) and luckily that worked fine. At 374K miles, this is my third set of plugs that I have installed and never had an issue before. I used a torque wrench set to 18 ft. lbs.

 

I just happened to change the plugs on my Corolla. The torque is 18 ft. lbs. One of my plugs was stripped, and so was the hole into which it threads. I had to clean up the threads with a tap (same size) and luckily that worked fine. At 374K miles, this is my third set of plugs that I have installed and never had an issue before. I used a torque wrench set to 18 ft. lbs.

How did you strip the hole and end up fixing it ?

 

I tighten with the wrench until it stops, then give it a last tap to ensure they're tight... done. Don't even use my torque wrench for them. Been doing plugs for like 25yrs now, never had issues.

 

Yeah, nothin' wrong with that. Some mechanics have a torque wrench built naturally into their hands.

 

I used the 18 ft. lb. torque spec yesterday on my plugs, per what was written in this forum's DIY on how to change the plugs. It felt like a correct amount of force to me.


I was also replacing my valve cover gasket. Putting the valve cover bolts back in, called for torque specs of 8 ft. lb. and 6.66 ft. lb. I tried to dial these on my torque wrench, but these were below the gauge marked on the wrench. I never got any kind of clicking sound using my torque wrench. I suspect that my wrench was not capable of torquing to such a small spec. EDIT: after reading more, my suspicion was proved correct. My tool wasn't capable of it and I was using the wrong tool for the job.

Fortunately, I'm not a dummy. I've been around the block with fixing cars for 12 years now, and know not to get in there overtightening stuff. I tightened everything up gradually, going round and round and round, jumping every 2 bolts so as to spread out the tightening. When I got to the point that I couldn't easily turn anything anymore, I stopped. Both the bolts and the block are soft aluminum, no sense stripping them!

Now for all I know, my results may be tighter than spec. Maybe when clamping a gasket, that's not actually good and I'll find something out the hard way. But I know they're not tighter than what they can handle. Hmm, unless the gasket expands. Guess I'd better read a little more. EDIT: after reading more, I decided to untighten all my bolts and then retighten them less aggressively, using a smaller non-torque wrench and going by hand feel. Just in case I shouldn't be squishing this gasket too hard. They're on "firm" now, but I'm not pushing them to the limit of what they will take, like before.

I think tightening spark plugs to spec is probably important, because I've seen 2 cars now that had loose spark plugs in them. I think when they are not done to spec, they vibrate over time and come loose. This could lead to firing problems.

 

Anti seize aluminum grease is a good idea.

 

All Toyotas I've ever worked on had gasket-seat spark plugs, you can feel when the gasket is crushed all the way. If you don't want to torque, then 1/8 turn past that is just fine.

That being said, I always put an in-lb torque wrench on it and torque to whatever the spec is. Note that NGK (and a lot of Japanese ACDelco) say not to use antiseize as the coating on the threads acts as antiseize, but I always use aluminum antiseize and torque to spec anyway. Some will say that the antiseize changes the torque; technically correct (the best kind of correct), but I've met very few cars that require indexed spark plugs (plugs that point a certain way in the combustion chamber to optimize combustion, when properly torqued. My Insights have them) and the torques on plugs are low enough that there shouldn't be any undue issues.

I've had to repair a 1GR plug hole with a Timesert after getting heads back from the machine shop for a head gasket job. The owner's brother changed plugs to try and deal with the misfire, so either cross-threaded it then or the machine shop did if and when they tried to chase the plug holes. Used a Timesert because I don't trust Helicoils for something exposed to a combustion chamber, the spark plug was sitting a bit back but no discernible effects.

 

You rarely go wrong with this:

Hand start to ensure you don't have them cross-threaded
Tighten with the socket wrench until it is snug
Do a 1/4 turn past snug, no more

Done. I don't think I have ever used a torque wrench on the God knows how many cars over the years. Fords, Hondas, Toyotas, Chevys...lost count.

 

I have never used a torque wrench on spark plugs, to seat the spark plugs I use the spark plug socket on an extension with no ratchet until it won't go any further with my fingers then I put the ratchet on and just give it a little tug to make sure it's down... gasketed spark plugs get a half turn after seating... Never reuse them, always replace if removed.

Tapered seat spark plugs get 1/16 turn and can be reused.

Some spark plug brands do not need an often recommend against anti-seize, such as NGK, especially if installing with a torque wrench as the anti seize makes the plug threads too slippery and causes over torque condition. This is not as much of a concern with the half or 16th turn method.

 

Now I am somewhat dreading replacing the spark plugs although I didn't kill them so I don't think it will be an issue but I'll either set the torque wrench lower or just hand tighten and do a quarter turn and that's it. I've heard the quarter turn from several mechanics in the past so that's what I'll stick to next time.

I put a shitload of anti seize on the NGKs b/c the person at the shop recommended it. Probably not the best idea.

 

When using anti-seize you just put a little bit, and that a bit up from the tip. I never use all of the little pack you get at the auto store - use maybe 1/4 of that small thing when I do use it.

 

I put a drop of oil on my finger and then run it through the thread on the plugs, have never had one seize on me yet.

Also again, I get to the end of the plug when it tightens... then do a quarter to half turn to tighten them, and done.