How do I know if I changed my own spark plugs correctly?


#1

I don’t have a torque wrench. I just have a spark plug wrench. I changed my own spark plugs. I don’t like taking them out and putting them back in. I’m not sure if I got the torque right. What should I do?


#2

The rule of thumb for spark plugs is, if the spark plug has a metal gasket seat, 1/4 turn once the plug is finger tight.

If the spark plug has a tapered seat, 1/8 turn once the plug is finger tight.

Tester


#3

Either buy a inch pound torque wrench, or use the shortest wrench handle you have. This will keep you from over torquing them. Remember you are not holding together a bulldozer and plugs need a light touch, especially if you have aluminum heads.

If they are not tight enough they will work their way out and the engine will get louder than normal. This usually leads to a broken coil if it is “coil over plug”, but not much else will get damaged.

But if you don’t like doing this, just pay someone else to do it.

Yosemite


#4

Tester, you mean 3/4 turn for the metal gasket seal don’t you?


#5

LOL, Keith, that’s the problem with “feel”. Everybody’s is different.

To teach kids the importance of proper use of barrel micrometers, I know someone who used to have a few of them measure a gage pin multiple times with a set that didn’t have the center piece that released when a specific torque was reached. The same kid using the same mics measuring the same pin three times in a row would get three different readings. Three kids each measuring three times would get none slightly different reading. Each kid had his own range of readings.

I know we’ve had lengthy debates about the importance of torque wrenches. For someone who’s installed hundreds or even thousands of spark plugs, as many of us have, it really isn’t critical. For someone new to working on cars, I personally think it’s critical, at least until he/she gets the feel of what the proper torque feels like.

To the OP, I’d suggest getting a beam-type torque wrench (about $25) and slowly bringing it up to the proper torque (engine cold) on each plug. If the plugs are under-torqued, it’ll get them properly installed. If none of them move, leave it as-is and use the torque wrench the next time. If nothing else, you’ll sleep better.


#6

The question is, how to determine if the plugs are tight enough?

A torque wrench is ideal.

But how many vehicles out there allow a straight shot to all the spark plugs where a torque wrench can even be used?

Not many.

So you have to use angle or feel.

Tester


#7

I was changing plugs a lot of years before I had a torque wrench. Now I have 5 of them and I still don’t use them on plugs.


#8

Tell me the torque you want and my hands will get it within 1-2 lbs…every time. That only took 20 yrs or so… I trust my Torque…do you trust yours? LOL

I bet Im not the only one on this site who can do this…

Blackbird


#9

I agree with @“the same mountainbike” .
Now that I’ve thought about it a little more, I think everyone new to wrenching on cars should invest in a torque wrench.
Once you use it enough you will know the feel for the correct torque when you cannot get a torque wrench into the space like @Tester mentioned.
As many have said, “everybody has a different feel” and only repetition will teach them “the feel”.

I watched a friends son yesterday almost go too far replacing a plug. He also needed to learn to support the head of the wrench to keep from breaking off a plug. He broke one trying to loosen it but I was able to get the rest out without a problem.

I think in the future I am going to incorporate a torque wrench with these kids for most of the work, so the get that “feel”.

Yosemite


#10

Yep…thats how it works…


#11

Don’t have a torque wrench and don’t want to purchase one? hmm … well, If they are installed and seem to be working ok, maybe just leave well enough alone. If they are too tight or too loose, eventually you’ll find out.


#12

I never use a torque wrench. I just tighten it until moderately tight and then start it up and make sure its not missing.


#13

Am I being overly suspicious if a brand-new forum member posts a comment that contains a link to a commercial product?

Hmmmmm…


#14

I wondered too, VDC. I’m inclined to give him the benefit of the doubt this once. He may be just pointing out what he uses. He did take the time to answer the specific question at hand.

Honda, I’d bet that you’re right that many of us could get the torque within range by hand… although I wouldn’t bet on +/- 1 ft/lb. I would point out, however, that the question was posted by someone brand new to installing spark plugs. For a newbie I’d have serious doubts. As a matter of fact, I wonder whether the average newbie even understands what ft/lb means. Heck, I’ve even seen debates on whether it should be ft/lb or lb/ft. Truth is, 20 lbs one ft away from the axis of rotation is the same as 1 lb 20 ft away.

To the OP, just out of curiosity, do you understand what a ft/lb is? I mean no offense whatsoever, I’m just curious… and if the answer is “not really” I’m very happy to consider this a learning opportunity. Nobody is born with this knowledge.


#15

The one that always gets my attention is INCH/lbs… I watched my buddy tighten his little valve cover bolts to 35 FT/lbs instead of Inch/lbs… Needless to say…that wasn’t a fun day… I would’ve thought he would have stopped by the 2nd bolt snapping…but no…

Blackbird


#16

Excellent edification. And good point to publish. That kind of an error could bring me to my knees… especially if I were the one who made it!


#17

and why are EZ outs called Easy ? I have yet to have an “Easy” time with any of them. They should be called “Curse Outs” Haha

Blackbird


#18

LOL, I too have never had an easy time with EZ outs. They don’t work like the commercial shows. Fact is, once the shank has married itself to the hole, it’s usually easier to bore it out oversize and retap it… or helicoil it if the size needs to be kept or if the base metal is soft like aluminum.


#19
The one that always gets my attention is INCH/lbs... I watched my buddy tighten his little valve cover bolts to 35 FT/lbs instead of Inch/lbs...

By the way, it’s in-lb and ft-lb (i.e., no division involved).

(Please don’t get started on lbf-in and lbf-ft; I’m too old to change…)

;-]


#20

This is spam…someone tried to post a link to the exact same bogus product a few months ago.