Tightening Spark Plugs without a torque wrench
May 16, 2014, 01:12 AM
#1
Tightening Spark Plugs without a torque wrench
Hey guys so i decided to check my spark plugs today just because i figured it had been a while since i checked them and they looked good so i put them back in. When i tightened them i got them snug then did about a 1/4 turn with the ratchet. on one of the spark plugs, as i was tightening it with the ratchet it kinda felt like it was starting to get easier to turn... i'm worried i possibly started to strip out either the spark plug or the spark plug hole itself. Is it possible that i over tightened it? Whats the worse that could happen if i did over tighten? (other than the spark plug blowing out of the hole). Doing a 1/4 turn with a ratchet after getting it snug is what i figured was necessary to ensure that it was tight enough. Thanks
May 16, 2014, 05:22 AM
#4
EvoM Guru
you only do a quarter turn on the first installation to seat/ crush the crush washer on the end of the plug to get a tight seal.
when you re install used plugs you should turn them down by hand with a socket and extension and then when they get tight just nip them slightly.
cranking another quarter turn on an already crushed crush washer is excessive by the sounds of it and you must really have been leaning on it. how long is your ratchet bar?
if it felt like it was getting easier to turn best thing to do would be remove the plug and have a look at the threads and try re installing it again and see how it feels.
when you re install used plugs you should turn them down by hand with a socket and extension and then when they get tight just nip them slightly.
cranking another quarter turn on an already crushed crush washer is excessive by the sounds of it and you must really have been leaning on it. how long is your ratchet bar?
if it felt like it was getting easier to turn best thing to do would be remove the plug and have a look at the threads and try re installing it again and see how it feels.
May 16, 2014, 06:11 AM
#5
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id say the worst that would happen would be needing to re-tap/replace the head. or possibly shavings falling into your cylinder if it stripped that badly. but the actual plug would likely not be what you stripped unfortunately
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May 16, 2014, 10:10 PM
#8
Would it be a good idea to pull it out again and check? I drove it today and did a pull 1st through 4th and the spark plug never popped out or anything so im assuming its probably ok. But with the way i am id have to take it out again just to know.
May 18, 2014, 07:58 AM
#13
I wouldn't worry about that, I think your fine. I remember a testing done a few years back, although on a domestic cylinder head, to test how much torque a spark plug would take before it would start to strip. IIRC they went somewhere around 90 ft lbs on a aluminum cylinder head and it was still fine. Not saying I approve cranking the spark plugs down like the Hulk, but just saying that so long as you did it with the head cooled down it would normally take quite a bit to ruin the threads unless you were somehow cross threading going in.
One other thing I have seen when you go to tighten plugs down and they start to feel like they are not snugging down well is that sometimes you may get debris or oil on the bottom. Make sure next time you put fresh plugs in to check that the spark plug holes are free of debris and oil. G/L
May 18, 2014, 09:14 AM
#14
I wouldn't worry about that, I think your fine. I remember a testing done a few years back, although on a domestic cylinder head, to test how much torque a spark plug would take before it would start to strip. IIRC they went somewhere around 90 ft lbs on a aluminum cylinder head and it was still fine. Not saying I approve cranking the spark plugs down like the Hulk, but just saying that so long as you did it with the head cooled down it would normally take quite a bit to ruin the threads unless you were somehow cross threading going in.
One other thing I have seen when you go to tighten plugs down and they start to feel like they are not snugging down well is that sometimes you may get debris or oil on the bottom. Make sure next time you put fresh plugs in to check that the spark plug holes are free of debris and oil. G/L
One other thing I have seen when you go to tighten plugs down and they start to feel like they are not snugging down well is that sometimes you may get debris or oil on the bottom. Make sure next time you put fresh plugs in to check that the spark plug holes are free of debris and oil. G/L
May 18, 2014, 09:21 AM
#15
yeah don't muscle them, I think the spec is like 17ft-lbs which is next to nothing. basically enough to crush the washer and seal it, you don't need to tighten them like a suspension component. If you used a 1/4" ratchet, that's smart because typically they are way shorter handles and long handles create more torque since it's force*distance