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Using a torque wrench in reverse is generally not a good idea.
Not only is that cr*p it doesn't even make any sense. You are arguing for ZERO CONTROL over a controlled approach to the application of force. Like THAT makes sense. Who cares if you stuff a torque wrench? (which you're not actually going to do). Torque wrenches are a hell of a lot cheaper to replace than a cylinder head.
 

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https://ricksfreeautorepairadvice.com/anti-seize-spark-plug-threads/

Some straight-forward info and also an interesting point about using anti-seize only if re-installing spark plugs that were once removed.

To the anti-seize on new plugs crowd, just be careful on torquing the plugs down.

NGK said:
NGK spark plugs feature what is known as trivalent plating. This silver- or chrome-colored finish on the threads is designed to provide corrosion resistance against moisture and chemicals.

The coating also acts as a release agent during spark plug removal. NGK spark plugs are installed at the factory dry, without the use of anti-seize. NGK tech support has received a number of tech calls from installers who have over-tightened spark plugs because of the use of anti-seize.

Anti-seize compound can act as a lubricant altering torque values up to 20 percent, increasing the risk of spark plug thread breakage.
https://ngksparkplugs.com/en/resources/5-things-you-should-know-about-spark-plugs
 

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Great question and two schools of thought:

Cold engine: Everything is contracted and removal can be more difficult, albeit aluminum is slightly tougher?

Warm engine: Everything is expanded and parts should come apart easier? Albeit aluminum is slightly softer.

We're splitting hairs, but if in my shop and confronted with what you have, I'd likely (?) try "warm".
 

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Not only is that cr*p it doesn't even make any sense. You are arguing for ZERO CONTROL over a controlled approach to the application of force. Like THAT makes sense. Who cares if you stuff a torque wrench? (which you're not actually going to do). Torque wrenches are a hell of a lot cheaper to replace than a cylinder head.
A few variables to consider here before jumping to any conclusions:

1. Not all torque wrenches work in reverse. If one were to assume theirs did when it actually didn't...they would effectively be using a mini breaker bar on seized spark plugs.

2. What if the calibration is off (which impacts many wrenches)? You could easily be applying double the torque that you set the wrench to, especially if setting the torque on the lower end.

The only torque wrench I'd be comfortable using in this application is a beam-style one, which provides the most control possible.
 

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My two cents - YMMV. Some Ford V8's have a 'spark plug ejection' problem do to a design oversight. When removing the plugs at the recommended service interval the aluminum threads in the head are damaged. Even though the new plugs are torqued properly the threads are weakened enough to 'pull'. After leaving the shop the plug flies out of the head - with the aluminum threads. BMW's do not suffer from this. The relevant point is Ford insists the plugs be removed with the engine hot. Some DIYers go so far as to change one plug a day after driving home from work.

On spark plugs that have compression type gaskets - like BMW uses - if you use anti seize on the threads do not use a torque wrench. Torque them with the 'angle method' described by the plug manufacturer. You will not over tighten them this way. For 'tapered' plugs without a compression gasket- like Ford uses - you must use a torque wrench with nothing on the threads. If you over tighten those on a Ford head you have a high risk of damaging the threads in the head.
 

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Not only is that cr*p it doesn't even make any sense. You are arguing for ZERO CONTROL over a controlled approach to the application of force. Like THAT makes sense. Who cares if you stuff a torque wrench? (which you're not actually going to do). Torque wrenches are a hell of a lot cheaper to replace than a cylinder head.

Alright, then I'll bite. At what point is the safe torque value (Nominal value sought) for the safe removal of a spark plug?
Without ego my hands have a very good idea of just how much torque I'm applying to any fastener w/o torque wrench, give or take a few ft. lbs. It's from experience, more than anything.

If there was a value for "go-no go" on removal of spark plugs out there (and if it was realistic?) I'd bet over 50% of the cars I touch would never get new plugs?

As I suggested it's an experience thing and through experience and feel, good technicians can tell if (usually) threads are being pulled.
Any critical part is then finished off with the torque wrench.

I'm here to help. ;>)) BTW....
 

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1. Not all torque wrenches work in reverse.
No sh1t Sherlock. You know what you call the ones that aren't? Pry bars. You really, really think you needed to point that out?

2. What if the calibration is off (which impacts many wrenches)?
When was the last time you had your arms calibrated? Sheeesh.
 

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Not only is that cr*p it doesn't even make any sense. You are arguing for ZERO CONTROL over a controlled approach to the application of force. Like THAT makes sense. Who cares if you stuff a torque wrench? (which you're not actually going to do). Torque wrenches are a hell of a lot cheaper to replace than a cylinder head.

Alright, then I'll bite. At what point is the safe torque value (Nominal value sought) for the safe removal of a spark plug?
Without ego my hands have a very good idea of just how much torque I'm applying to any fastener w/o torque wrench, give or take a few ft. lbs. It's from experience, more than anything.

If there was a value for "go-no go" on removal of spark plugs out there (and if it was realistic?) I'd bet over 50% of the cars I touch would never get new plugs?

As I suggested it's an experience thing and through experience and feel, good technicians can tell if (usually) threads are being pulled.
Any critical part is then finished off with the torque wrench.

I'm here to help. ;>)) BTW....
Sure.

Let's deal with the idea that it can harm your wrench first. Before we start it must be said that you can damage a torque wrench in either ACW or CW mode if you ignore the click that informs you that the set limit has been reached. You can actually use a torque wrench as a normal wrench in most cases if you don't care about its health and just keep swinging on it like it's a breaker bar. You can use it as a hammer if you like. So there is nothing special where ACW mode is concerned in that regard.

So what makes you think the wrench gives a toss about whether it is loosening a right hand bolt or tightening a left hand bolt when it is in ACW mode? It is designed to apply a rotating force in an ACW direction up to a limit that you set that you can onlt set within the design limit of the tool?

As for what you set the tool to initially you start 15% below the documented torque for the application, whether it's a plug or not, and you apply the torque. If the torque wrench clicks before you get to the documented torque you increase the torque setting and try again. At some point the fastener (or in this case the plug) will move before the wrench clicks. Limit yourself to 115% of the documented torque. If that doesn't shift it then you know you have a problem and that care or special engagement is required. It is impossible to determine that manually and the first you are likely to know about it is when the threads fail or the fastener shears.
 

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I've always done plugs when the engine is cold.



NGK, who makes the plugs, says to not use anti-seize which is where the recommendation comes from.

You can still use it, but need to be super-careful when it comes to torquing them down (same reason why anti-seize isn't recommended on wheel bolt threads).

What the OP is experiencing is unusual. I pulled original plugs at 110K miles with no issues and that was without any anti-seize from the factory.
The last plug I pulled had even resistance all the way out, more than I expected but it didn't increase. I replaced it and haven't had a problem.
 

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And people get flamed for suggesting a little anti-seize on the threads when installing plugs.

If it was meant to have anti-seize don't you think the manufacturers would slap a bit on the threads like they do with O2 sensors and glow plugs?
 

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No sh1t Sherlock. You know what you call the ones that aren't? Pry bars.
Torque wrenches that don't work in reverse...are still called torque wrenches. :idea:

What do pry bars have to do with anything?

You really, really think you needed to point that out?
Generally, no. However, in response to your silly suggestion to use a torque wrench to loosen spark plugs, the obvious was politely stated.

You can be as riled up as you'd like. Fact is your bad "advice" could lead to some poor schmuck snapping a seized plug in the head when they grab a 3/8 Crapsman clicker that is badly out-of-calibration and not realize how much mechanical leverage is being applied to a very brittle part.

When was the last time you had your arms calibrated? Sheeesh.
Good one, Ray. Let's see what you come up with next time.
 

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Torque wrenches that don't work in reverse...are still called torque wrenches. :idea:

What do pry bars have to do with anything?
It was a joke. Christ!!

Generally, no. However, in response to your silly suggestion to use a torque wrench to loosen spark plugs, the obvious was politely stated.

You can be as riled up as you'd like. Fact is your bad "advice" could lead to some poor schmuck snapping a seized plug in the head when they grab a 3/8 Crapsman clicker that is badly out-of-calibration and not realize how much mechanical leverage is being applied to a very brittle part.
You are clueless. Champion Auto parts. Manufacturers of spark plugs and glow plugs for 112 years. Maybe they know better than you hey? You should educate yourself before you call others out.

"First off: Only remove and fit glow plugs using a manual torque wrench".

Same process for glow plugs and spark plugs is recommended.

https://www.championautoparts.co.uk/technical/light-vehicles/ignition/installation-guides/glow-plug-installation-and-removal.html
 

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You are clueless. Champion Auto parts. Manufacturers of spark plugs and glow plugs for 112 years. Maybe they know better than you hey? You should educate yourself before you call others out.

"First off: Only remove and fit glow plugs using a manual torque wrench".

Same process for glow plugs and spark plugs is recommended.

https://www.championautoparts.co.uk/technical/light-vehicles/ignition/installation-guides/glow-plug-installation-and-removal.html
C'mon Ray, you forfeit the right to call anyone clueless on the topic when you post instructions for glow plugs. :rofl:

No, they are not same. Not even close. Seized spark plugs are rare while seizing is inevitable when it comes to changing glow plugs. You know this, too, so why put them in the same boat?

I checked their spark plug process. Says to use a torque wrench to loosen (probably to keep it simple with one tool since there is no mention of setting any torque) but also places caution on stopping immediately if seized.

May I suggest you use a torque wrench to undo the plugs to reduce the risk of stripping them?
This, is BS my friend. You are relying on an instrument to give you a safeguard that is likely not accurate in the first place.

Very simple scenario:

1. A plug is seized.
2. You set your torque wrench (assuming it goes in reverse) to a safe breaking torque.
3. The torque you set it to is wildly off.
4. Thinking you're safe, you keep gradually applying pressure.
5. Snap.

A safer option is to use a 1/4 drive ratchet. Go by feel and scale up to a standard length 3/8 drive if needed. If that doesn't easily work, penetrating fluid.
 

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Daaaang, my browser just refreshed after posting and saw all the mornings posts ...

Removing plug with hot engine could strip the softer hotter threads. Cold head has stronger threads.

Old plugs might have the protruding threads covered with burned oil and hard carbon; hence it broke loose then jammed by the mentioned dirty threads.

Go slow easy back/forth with lube oil, and best of luck.
Any idea above what temperature aluminum alloy begins to weaken? Or, better yet, does Al alloy maintain its strength until a certain temp is reached and then it weakens?

I googled this a bit and found some threads suggesting that above 350F al alloy weakens. A different guy in same thread says stay below 200C, but that's not far from 350F.

https://www.practicalmachinist.com/vb/general/highest-temp-heat-aluminum-casting-remove-stuck-fastener-273942/

If weakening begins at 350F (~ 176C), that is way hotter than the "warm" temp (by hand feel) that I would typically be trying to remove a spark plug at.
 

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Discussion Starter #38 (Edited)
. Do you think the aluminum gets that hot? The coolant is maintained at 94C. I know it is not exactly apples to apples, but I would not think the Al gets twice as warm, if that is what you're suggesting.

Edit: I suppose one could use a heat gun on an exposed piece of the head to get an idea.

Regardless, after my experience last evening I will not attempt extraction w a hot engine. Ill shoot for cold or just warm as recommended by others in this thread.

Even w all the digressions that have taken place here, this thread has been very useful so far and I appreciate it!
 

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Where does one even begin to look up the maximum loosening torque?

Champion seems to be the only place that it's mentioned and even they don't list a spec. It has to be greater than the tightening torque, but how much is too much? With a question like that is there any point in asking if the tool is calibrated or not?
 

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Ok, maybe this is the real reason why not removing plugs with hot engine: aluminum head expanded more than steel plug threads, length wise. This would cause more friction on the threads and so the removal torque needed to be higher than room temperature.
 
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