Yeah, call them when you encounter one of their plugs that’s stuck. See how much “support” you’re going to get.
Their recommendations are to protect them, not to make your life easier.
Changing Spark Plugs and Lubrication
- Thread starter RaymondP
- Start date
Their recommendations are to protect them, not to make your life easier.
It's on the replacement sensors we get at the dealer aswell.
- Joined
- Nov 29, 2021
- Messages
- 5,383
Now you've got me wondering how that can happen. Stuck, like, can't get it out when the spark plug socket is actually on the plug with a nice firm loosening motion? Are these cross-threaded, these stuck plugs?
I know people sometimes say to put some antisieze on the threads... then the debate becomes how much... though I'm again skeptical if you need to do this.
Yes they may feel like they’re cross threaded, but are not. They may break or pull the threads out from the head.
In most cases they’re just more difficult to remove then normal, or may require some back and forth turning, but come out OK.
Here are some examples.
https://bobistheoilguy.com/forums/threads/big-problem-any-way-to-get-this-out.359983/#post-6240971
https://bobistheoilguy.com/forums/threads/spark-plugs-binding-on-removal.339854/#post-5738342
Certain engines were prone to this. Stainless plug / aluminum head - galvanic corrosion and its stuck. Yes, it will come out - but it will bring the threads with it. Its somewhat vehicle specific it seems.
NGK at least coats the threads with their own sort of anti seize. I have never had a NGK plug seize.
The only issue adding your own anti seize is the torque spec is no longer accurate. The torque spec is without wet lube, and its really difficult to spec down from that because it depends on many variables, so you could strip it on tightening. I have used anti seize, but I don't use a torque wrench, I was taught by a master 40 years ago how to feel the threads settling in. I don't recommend my way unless you have a master of your own around to tutor you for the next decade or so.
The torque argument is quite strange to me, not that it’s invalid, however, yes a lubricant will affect the torque wrench reading, but so will dirty/sooty threads, somehow people don’t think about that.
Who in here runs a thread chaser in the head to clean up the threads? I’m pretty sure not many if any. It’s kind of strange from the “by the book” people to miss this crucial step if they are so worried about torque.
All torque specifications are for clean threads, most are dry, some are wet, but all of them have to be clean, on both sides, nut just one. How come that is never brought up?
Who in here runs a thread chaser in the head to clean up the threads? I’m pretty sure not many if any. It’s kind of strange from the “by the book” people to miss this crucial step if they are so worried about torque.
All torque specifications are for clean threads, most are dry, some are wet, but all of them have to be clean, on both sides, nut just one. How come that is never brought up?
- Joined
- Nov 29, 2021
- Messages
- 5,383
Even I know the threads should be clean. First thought was.. maybe a burst of WD40/BPC down the holes, aimed at the threads? The BPC would evaporate quickly, the WD40 would just get pushed out on the exhaust stroke, nothing major, (assuming you have a clear shot to the hole as so many engines do not) - I don't work in a shop, but I'd almost bet they would view loading up a thread chaser (again, to a very hard to access spark plug hole) to have to un-do then re-do the cleaning in that way.. could literally be viewed as double work.. (shop logic?)
I've cleaned holes with sprays. Maybe use a paper towel not rag to wipe just to make sure, perhaps feel the threads. IF they were easy to get to. Some engines they are just right there on top and there isn't much to it. It's when you need two extensions in various exotic configurations with flex sockets to get on some or maybe all of them to some extent....
TTBOMK I've not encountered a stuck plug. Even on Heat Range 5 plugs. Can't really comment on plug quality except that I've also never had an issue with NGK.. Other plugs are likely fine, some may have issue, but for Japanese vehicles I'd select NGK
German I'd go OE (IS it Bosch? Never had luck with Bosch plugs. I would get OEM/OE)
American.. again, probably OE since only manufacturers I can think of are ACDelco, Motorcraft, Champion (and the eternal question.. who makes them.. I can't see that being NGK.)
Last edited:
Two answers - in a modern aluminum head you have likely 10-12 threads on the plug minimum, which only the bottom one might have some carbon, and the new plug will pass through that before the washer sets and self clean it out anyway - so likely very minimal torque change,
But the most important fact is the carbon would cause the plug to be under tightened - so it might not run right which would throw a code. The lube causes over tighten - AKA strip the thread. Which is worse?
For the record I have never had a properly running engine with a plug thread hole that had carbon in it. Those threads are very precise, at least on Japanese builds. My lawnmower - sure.
Cleaning the plug threads by blasting carbon junk into the cylinders is worse than leaving them alone. The gunk doesn’t magically disappear because you hit it with solvent.
I chase threads when needed. For sparkplugs, I have an old sparkplug, with grooves cut transverse to the threads. Most thread chasers are too big for the sparkplug wells on my cars.
I have had bad experiences with shops that goop a bunch of anti seize on the threads of the plugs. Most recently on the V70R. I thought the plugs were seized. Nope, just had so much anti seize on the threads that the plugs were extremely difficult to remove. It had been serviced at a European Auto “specialist”, including several spark changes.
Demonstrating, once again, the difference between people who get paid for a job, and those who actually know what they’re doing.
No, those are extremes or most likely misuse of the equipment or lack of experience.
Torque is not specified to the point where if you go over you’re stripping threads or if you go under things loosen up on their own. That’s not how it works, there is a built in tolerance. The standard is usually around +/- 10%.
The engineers understand perfectly fine that plug threads can be oily from a leaky seal or carboned up and cannot be cleaned to brand new condition or sometime at all due to location. So that’s built into the tolerance in the service manual.
The only reason I brought it up is to show how people obsess about only one aspect of things. And if one obsesses about overtorquing they should also be obsessing about undertorquing. Which I guess is the reason it’s called OCD, because it’s not based on logic and reason but on fear.
The engineering spec will also inlcude whether its dry or lubed, and for plugs its almost always dry - but check your FSM. 10% of 18ft lbs could easily be taken up by a lubed plug and a chinese torque wrench.
I am not dismissing under tighten theory - only that the fix for an under tightened plug is much easier than a stripped one. The likelyhood of stripping a plug depends a lot on the vehicle.
It is standard practice in many industries to follow the service data provided by the OEM if the data provided by the part manufactor is different. Here is an example that applies to this thread-Honda's service data says to use anti-seize on NGK plugs (I'm with Honda on this one).
- Joined
- Jul 22, 2022
- Messages
- 830
I was thinking there would be a lesser amount of rotation when lubricant is applied.
With an angle it will be agnostic to the torque value.
No, there would be more rotation. When threads are torqued, they “grind” against each other creating friction, the more you rotate, the more contact and friction threads create because of the shear forces applied. Engineers know the type of metal and it’s coefficient of friction and based on that can calculate torque requirements. That’s because a click or beam type torque wrenches work on this friction. In other words there needs to be an opposing force aka friction for them to click at a specified setting. Or bend the handle in the beam type style TQ wrench.
By applying antiseize, which is a lubricant, you reduce that friction, hence it will take more rotation to get to the same opposing friction to make that wrench click. But that forces the threads to create even more shearing forces against each other since thread pitch is the same and the actual rotation dictates how much shearing forces they produce. That is why applying a lubricant to the threads and not lowering the torque setting, can shear off the threads.
By going with angle of rotation, you eliminate the friction variable and the shearing forces on the threads will remain the same.
- Joined
- Jul 22, 2022
- Messages
- 830
In my two posts with @kschachn I was only concerned about angle of rotation and not torquing, but thanks for your input.
excellent advice. back before I had all those tools and equipment available to me I would drive to the gas station and put a quarter in the air machine and hold down the nozzle and blow out all the gunk around the spark plugs. then I'd go home turn the car off lift the engine Hood up call over my buddy and we would order a pizza and have a six pack of beer. as far as putting anything on a spark plug or the threads I used a toothpick and got just enough on the tip and put it on the top two threads. I think one packet lasted like 5 years. the biggest concern my dad explained to me was you don't want that stuff seeping down into the engine. was also very quick to instruct me to try to thread them on with my hand or with an extension and if there was any resistance to back it out and get somebody else to look at it with you and give you some assistance. don't want to be having to do a tap on the spark plug hole. in all honesty I think sometimes it's harder for people to ask for help that it is anything else some people feel that they should just be able to do it but I would always tell people if in doubt back it out.
This is from 2002, what do the new service manuals say?
Whenever I removed any factory plus I don't recall ever seeing remnants of a factory paste.
Blow out the hole w air, add a tiny dab of anti-seize towards the end of the plug (every plug) and tighten to tight on a short grip of the wrench(~15-20ish lbs I'd say), gtg.
I had my old Ascender(trailblazer) that had og plugs in it when I bought at 85k, I changed at 100k per manual and thought threads were coming out as they were stuck fast. Horrid screech with every turn of the wrench even w working on blaster back and forth. Went to 50k the next time and never let plugs go beyond that anymore don't care they say good for 100k, plugs are cheap enough. Old coppers get changed at 15k now. Had this nasty experience w my kids old Volvo, Mazda protege and my ex's Merc never fun thankfully no threads came w. If any seam stuck, I work pb blaster into them and let them sit for an hour or two before proceeding.
I had my old Ascender(trailblazer) that had og plugs in it when I bought at 85k, I changed at 100k per manual and thought threads were coming out as they were stuck fast. Horrid screech with every turn of the wrench even w working on blaster back and forth. Went to 50k the next time and never let plugs go beyond that anymore don't care they say good for 100k, plugs are cheap enough. Old coppers get changed at 15k now. Had this nasty experience w my kids old Volvo, Mazda protege and my ex's Merc never fun thankfully no threads came w. If any seam stuck, I work pb blaster into them and let them sit for an hour or two before proceeding.
On all my Hemi’s I used a small amount spread thinly on my NGK plug threads never an issue in or coming no back out.
