Changing spark plugs- Do I need a torque wrench? (Mazda3)

[JEDI]

2005 Mazda3i automatic, 100k miles

When I had my '93 Sentra, i changed spark plugs w/o torque wrench.
once at 100k, and another at 200k miles. No problems.

Do I need a torque wrench with modern cars, such as a Mazda3?

 

[Kaervak]

I've never used a torque wrench. Start the plugs by hand, thread them in until you feel resistance and then turn them maybe 1/4 turn more with a ratchet. Oh, change them when the engine is cold. Doing it hot could possibly strip the threads in the cylinder head and use anti-seize on the plug threads.

 

[CraigRT]

No torque wrench, just good and snug, or you will lose compression through the spark plug threads.

 

[exdeath]

Just snug them up when cold, never when hot. It should be tight enough that it takes some "pop" to break them loose, but easily with one hand around the ratchet head.

 

[Zorba]

If you have a torque wrench why not? I use a torque wrench, since I have it, I wouldn't go buy one just for spark plugs.

Engineers spec a certain torque for a reason, so IMHO it is a good practice to use what is spec'd.

 

[zerocool84]

Technically yes you are supposed to torque them to the spec listed in the owners manual but I don't know anyone who ever does that and I never have on any cars I've done it on. Just be VERY careful when putting them back in. Cross-threading spark plugs could mean needing new heads. Don't know if the Mazda 3 has aluminum heads but be careful and start threading them by hand at first or with a long hose attached at first to get them started.

 

[PricklyPete]

Since I own a torque wrench...yes...I do it every time. I didn't on earlier cars as I didn't own one. It is a tool worth owning if you plan on doing a lot of work on your car...but they do cost a decent amount for a good one.

 

[bruceb]

If it is an aluminum where the spark plugs are threaded into, then you should put a small amount of antiseize on the plug threads and if there is enough room, use the torque wrench. If not, hand snug, then about 1/2 turn with the socket is fine.

 

[lavaheadache]

I'm mostly gonna reiterate what has already been said. A torque wrench is not a neccesity but common sense is. Almost all engines today use aluminum heads and are very easy to strip out. I would say a general rule of thumb for spark plugs is 20 ft/lbs of torque. With a 3/8 ratchet, 20 ft/lbs would be a little more than half the effort of taking off an ocean spray cranberry juice cap for the first time. Bottom line... not much unless you are my 83 year old grandmother who thinks they never cut the ring enough and wants to sue for arthritis pain. Now i just preturn all the caps. I told her i called them and bitched em out, lol. Dementia is a great place. =)

 

[TridenT]

I always use a torque wrench for those. My car runs at 1,000,000,000 hp because of it.