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Old 05-07-2019   #1
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1.2 petrol spark plug torque?

As it says in the title - does anyone definitely know the recommended torque for the spark plugs on a 2012+ 1.2 petrol engine panda?
I've searched on this site and everywhere else and can't get an actual figure. All the posts just say 'use the correct torque' but never state what it is.
I've just started a service and the first plug could be undone by hand without any effort or leverage, I'm certain that's not correct.
New air filter & correct NGK plugs have been fitted and it seems much more lively, smoother & quieter - but if a plug was loose then that follows.
I'd like to get the plugs correct before I continue with the rest.
Also any ideas for the sump plug setting?

Thanks
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Old 05-07-2019   #2
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Re: 1.2 petrol spark plug torque?

Check the NGK-site. Im pretty sure though it'll say 25 Nm.

gr J
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Old 05-07-2019   #3
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Re: 1.2 petrol spark plug torque?

I don't know the figure, but I've always gone with (after taking advice from people here) "finger tight, then 1/4 turn with a ratchet".
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Old 05-07-2019   #4
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Re: 1.2 petrol spark plug torque?

Quote Originally Posted by A3jeroen View Post
Check the NGK-site. Im pretty sure though it'll say 25 Nm.

gr J
25 to 30Nm sounds about right as does Eklipse's "old school" 1/4 turn (I like old school!). Torquing spark plugs gives me a problem because, and yes I know it's controversial, I like to apply a light coating of copper or aluminium anti seize grease to the threads before installation. This, of course, makes the threads "slippy" so makes a nonsense of using a torque wrench because you will over tighten and possibly strip out the threads. So why do I do this? because I've come across enough seized in plugs in my time to know I don't want to have to deal with one in the family vehicles. I've never had one of my greased plugs seize.

So tightening without a torque wrench? Well, for me, not a problem as I've been doing it for the best part of 50 years and I've developed a very good "feel" for what the correct tightness is. I can't transfer that to you here but I can make this suggestion. Take a standard new spark plug (the type with a crush washer) like are used in our FIRE engines and install it carefully (because you don't want to cross thread it believe me) twisting it into it's hole by at least a couple of turns by hand before you go anywhere near it with your socket and "T" handle/ratchet. Run it right down the thread until it just "snugs" the washer firmly up between the shoulder on the plug and the surface of the head. This is the point at which you need to exert considerably more force to tighten it further.

So now let's think about what we are trying to achieve here? We want a gas tight seal between the head and the plug. This is where the "crush" washer comes in. Correct tightening of the plug will cause this special washer to "crush" down and take up any slight imperfections between the shoulder of the plug and the face of the threaded hole you are screwing it into. (you did clean up the facing where the washer contacts the head didn't you? Well done if you did because many don't and if you don't you risk damaging this face and failing to achieve a proper seal) As long as you have a reasonable sense of "feel" in your hands/fingers you can feel this crush happening. So, if we go back to our plug which we've just run into it's hole to the point where it's just "pinching" it's washer, if we now start tightening further you'll find it takes a bit of force compared with when we were just "running" the plug down the hole but you'll go about another 1/4 turn or so needing to apply only moderate force. This is the "crush zone" where the washer is being "squashed". It can be a little alarming the first couple of times you do it because it feels quite like a threaded fixing feels when it's stripping it's thread and your natural reaction is to stop tightening! As you continue to tighten into this "crush zone" you will then find the plug will suddenly get really tight to turn - stop immediately! Congratulations, you've successfully crushed the washer and your plug is now correctly installed!

Back in the days when I taught basic mechanics I had a number of old cast iron heads bolted to a workbench and all my students learned this way to install plugs. There are other types of plug (taper seat) which don't use washers so you can't use this method with them but once you have the "feel" for how tight a plug should be you can install pretty much any spark plug with just a socket and "T" bar. (going by Eklipse's 1/4 turn method you would be going an 1/8 turn with a taper seat) Of course this "feeling the crush" method only works with a new plug which has a new uncrushed washer. So if you are reinstalling a used plug it's even more useful to have developed "the feel". I found this especially useful when I worked on DAF cars where the air cooled engines used a very short reach plug which was easily stripped. (we did a fair trade helicoiling plug holes in them for other garages!) Older lawn mower engines are also quite notorious for it too as their "flathead" engines used very short reach plugs which are often stripped out by hamfisted gardeners.

Lastly can I just say, try doing up a few plugs, or even nuts and bolts, to 25Nm with a torque wrench, then undo them again. They don't feel all that tight do they? In my experience a lot of plugs are needlessly over tightened when installed. It's the crushing of that washer which is the important factor. (unless of course you have taper seat plugs - I don't think Fiat are into them are they? - in which case its firmly seating the taper which matters. But again it doesn't need to be "super tight"). Ideally you should always fit a new uncrushed washer every time you reinstall a plug - you can buy them in packets - but not many people bother. Need I say that if you decide to have a go at this and "mess up", as our American cousins would say, don't come crying to me please. It's all a matter of feel and that's impossible to teach from a distance.
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Old 05-07-2019   #5
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Re: 1.2 petrol spark plug torque?

Quote Originally Posted by Pugglt Auld Jock View Post
25 to 30Nm sounds about right as does Eklipse's "old school" 1/4 turn (I like old school!). Torquing spark plugs gives me a problem because, and yes I know it's controversial, I like to apply a light coating of copper or aluminium anti seize grease to the threads before installation. This, of course, makes the threads "slippy" so makes a nonsense of using a torque wrench because you will over tighten and possibly strip out the threads. So why do I do this? because I've come across enough seized in plugs in my time to know I don't want to have to deal with one in the family vehicles. I've never had one of my greased plugs seize.

So tightening without a torque wrench? Well, for me, not a problem as I've been doing it for the best part of 50 years and I've developed a very good "feel" for what the correct tightness is. I can't transfer that to you here but I can make this suggestion. Take a standard new spark plug (the type with a crush washer) like are used in our FIRE engines and install it carefully (because you don't want to cross thread it believe me) twisting it into it's hole by at least a couple of turns by hand before you go anywhere near it with your socket and "T" handle/ratchet. Run it right down the thread until it just "snugs" the washer firmly up between the shoulder on the plug and the surface of the head. This is the point at which you need to exert considerably more force to tighten it further.

So now let's think about what we are trying to achieve here? We want a gas tight seal between the head and the plug. This is where the "crush" washer comes in. Correct tightening of the plug will cause this special washer to "crush" down and take up any slight imperfections between the shoulder of the plug and the face of the threaded hole you are screwing it into. (you did clean up the facing where the washer contacts the head didn't you? Well done if you did because many don't and if you don't you risk damaging this face and failing to achieve a proper seal) As long as you have a reasonable sense of "feel" in your hands/fingers you can feel this crush happening. So, if we go back to our plug which we've just run into it's hole to the point where it's just "pinching" it's washer, if we now start tightening further you'll find it takes a bit of force compared with when we were just "running" the plug down the hole but you'll go about another 1/4 turn or so needing to apply only moderate force. This is the "crush zone" where the washer is being "squashed". It can be a little alarming the first couple of times you do it because it feels quite like a threaded fixing feels when it's stripping it's thread and your natural reaction is to stop tightening! As you continue to tighten into this "crush zone" you will then find the plug will suddenly get really tight to turn - stop immediately! Congratulations, you've successfully crushed the washer and your plug is now correctly installed!

Back in the days when I taught basic mechanics I had a number of old cast iron heads bolted to a workbench and all my students learned this way to install plugs. There are other types of plug (taper seat) which don't use washers so you can't use this method with them but once you have the "feel" for how tight a plug should be you can install pretty much any spark plug with just a socket and "T" bar. (going by Eklipse's 1/4 turn method you would be going an 1/8 turn with a taper seat) Of course this "feeling the crush" method only works with a new plug which has a new uncrushed washer. So if you are reinstalling a used plug it's even more useful to have developed "the feel". I found this especially useful when I worked on DAF cars where the air cooled engines used a very short reach plug which was easily stripped. (we did a fair trade helicoiling plug holes in them for other garages!) Older lawn mower engines are also quite notorious for it too as their "flathead" engines used very short reach plugs which are often stripped out by hamfisted gardeners.

Lastly can I just say, try doing up a few plugs, or even nuts and bolts, to 25Nm with a torque wrench, then undo them again. They don't feel all that tight do they? In my experience a lot of plugs are needlessly over tightened when installed. It's the crushing of that washer which is the important factor. (unless of course you have taper seat plugs - I don't think Fiat are into them are they? - in which case its firmly seating the taper which matters. But again it doesn't need to be "super tight"). Ideally you should always fit a new uncrushed washer every time you reinstall a plug - you can buy them in packets - but not many people bother. Need I say that if you decide to have a go at this and "mess up", as our American cousins would say, don't come crying to me please. It's all a matter of feel and that's impossible to teach from a distance.
Just rereading this and it occurs to me to mention something you should do when removing plugs. It's not uncommon to find that there is dust/grit/etc around the base of the plug which has accumulated since when the plugs were last changed. Some engines are better than others in this respect - for instance my older boy's Astra has a one piece coil pack which completely closes off the spark plugs and excludes dirt. You really need to prevent any chance of this dust, or even worse grit, getting into the cylinder when you remove its plug. In the workshop, and now at home, I had/have access to compressed air but when I was younger, if working at home I had a length of small diameter hose with an air jet in the end and the other end fitted to my foot pump - I still have it and sometimes it's still useful if I can't easily get a car up to my garage door. Firstly slacken the plug by a couple of turns or so (which gives access to the first couple of threads and loosens deposits) and then give it a good blast of air to blow the debris away from the plug thus stopping it falling into the engine. Now unscrew the plug and remove it. Examine the seating in the head and clean further if necessary (I use a rag dampened with carb or brake cleaner). An unexpected bonus of my practice of lightly applying anti seize to plug threads is that it helps to trap small bits of debris and further prevents them falling into the plug hole. You sometimes have to be quite inventive with plugs that "live" at the bottom of very deep "holes"
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Last edited by Pugglt Auld Jock; 05-07-2019 at 21:51.
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Old 06-07-2019   #6
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Re: 1.2 petrol spark plug torque?

Quote Originally Posted by t0neloc View Post
As it says in the title - does anyone definitely know the recommended torque for the spark plugs on a 2012+ 1.2 petrol engine panda?
15-20 Nm. See the attached extract from the NGK plug guide.

Fiat eLearn shows 17 Nm for 12mm plugs.

Others have nailed it already; relying on a torque wrench setting is neither necessary nor helpful when fitting spark plugs. Most standard automotive torque wrenches aren't usable at such a low torque figure; you'd need a specialist torque wrench such as the kind used on motorcycles.

Most folks seriously overtighten spark plugs (and that applies equally to many working in the trade). Old timers will know by feel how to tighten up a plug; personally I'd suggest the angle method as has already been described for those with less experience. Bear in mind that small diameter plugs in aluminium heads should only be tightened to about half the torque you'd use on an old style full size 14mm plug in an iron engine.

I've taken out many spark plugs from factory fresh engines for the first time; surprisingly little torque is required for removal. Those in secondhand cars that have been changed before are generally much tighter, and incorrectly so.

I've also attached a copy of the NGK quick reference guide from which the spark plug figures were extracted - it's a useful pocket reference.

Quote Originally Posted by Pugglt Auld Jock View Post
I like to apply a light coating of copper or aluminium anti seize grease to the threads before installation.
Me too; I generally grease all bolts when refitting. As you say, it's very easy to overtighten greased bolts.

Some manufacturers actually provide both dry and greased torque tightening values; in the absence of published data, use between 1/2 and 2/3 of the dry settings if you do apply a lubricant.

What you absolutely must do if you do apply grease is to degrease and reapply every time a bolt is removed and replaced; one piece of grit or other debris on the thread could seriously impair correct seating and tightening of the bolt.

Quote Originally Posted by t0neloc View Post
Also any ideas for the sump plug setting?
It's a tapered thread plug (there is no washer). I've not seen any published values, but pulling it up with a standard 1/2" ratchet handle so that it is just firm works for me. Again, be careful not to overtighten or you'll likely be replacing the sump. Whatever your preferences regarding lubricated bolts, this one always will be.
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Attached Files
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Last edited by jrkitching; 06-07-2019 at 07:55.
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Old 06-07-2019   #7
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Re: 1.2 petrol spark plug torque?

Thanks for that JRK. and for including that chart. Life's got much more complicated now-a-days with all the different sizes. I remember vividly the small diameter (for those days) taper seat plugs fitted in the OHC slant engines in the Vauxhall victor FD and FE, also the Bedford CF (had to buy a new socket to fit these) because they used to jam in place and shear off leaving the threaded portion in the head and you holding the electrode and hex head in your hand! The CF was a bitch to work on the plugs too as they were hiding under the scuttle just to entertain. Made life very difficult if you broke one! I also remember those large diameter taper seat plugs in the Ford Pinto engine (Cortina etc) which, I think because they were so big, were nearly always tightened to a ridiculous degree. The heads were cast iron and corrosion wasn't usually a problem, it was just that people did them up far to tight.

Interesting about the taper fit sump plug in that I've found most I've encountered during my life have been over tightened to a greater or lesser degree. I've thought about this from time to time and I think it's the lubrication that's the problem. The engine oil, which unavoidably saturates the thread when draining, makes tightening a very smooth and easy operation with little resistance so people are actually overtightening because they are not feeling the resistance they would if no lubrication were present consequently the plug is "rammed" into the taper more deeply than would otherwise be the case. Then, over the course of the year or so before the next oil change is done, the oil "squeezes" out (repeated heating and cooling - expansion and contraction - probably helps) so when you come to remove it you find it's gripping into the taper really tightly. By the way, can I advise people not to wrap the thread with plumbers tape? The problem with this practice is that there is always a chance some of the tape may become detached and get stuck in the oil pump pickup strainer which is obviously not to be recommended.
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Old 06-07-2019   #8
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Re: 1.2 petrol spark plug torque?

In all my days of in & out of the automotive industry, never torqued a spark plug.

Just to add, I've had problems in the distant past of removing the odd plug though, but that as they say is a whole different story...
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Last edited by jimboy; 06-07-2019 at 09:54.
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Old 06-07-2019   #9
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Re: 1.2 petrol spark plug torque?

Talking about spark plugs, have you seen the threaded length of the ones used in the 1.4 Kia Rio? I'd definitely be lubing them!
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Old 06-07-2019   #10
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Re: 1.2 petrol spark plug torque?

Many thanks to everyone for the advice. My experience in mechanics is mainly on older cars and motorbikes where there's usually a figure to work to & I have the necessarily sensitive torque wrench to do it. That said, I do have a feel for when to stop. I wasn't sure if the more modern engines needed different treatment, clearly not.

In the end I went with the advice on the NGK box & website that says a 1/2 - 2/3 turn once seated. It's certainly not the easiest engine to get the plugs in and out of being at the bulkhead side of the block. Out of interest I then used a torque wrench starting at the lowest setting and working up until it just registered. All came out about 18 lbs/ft which equates to 25Nm.

In the old days I also used grease on the plugs as others have suggested because the risk of not getting them out again was greater than the risk of me over-tightening them especially with plugs at the front of the block and exposed to water.

When fitting plugs, bolts, nuts etc I always place it on/in and turn it counter-clockwise until I feel it drop into the thread. This avoids cross-threading and if you can't then turn it in by hand very easily, go back and try again. Always go in as far as possible by hand before using leverage from tools.
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Old 06-07-2019   #11
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Re: 1.2 petrol spark plug torque?

[QUOTE=t0neloc;4488065]



In the old days I also used grease on the plugs as others have suggested because the risk of not getting them out again was greater than the risk of me over-tightening them especially with plugs at the front of the block and exposed to water.

Had a wee laugh to my self when I read "IN THE OLD DAYS" When was that tOneLoc?
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Last edited by jimboy; 06-07-2019 at 11:39.
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Old 06-07-2019   #12
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Re: 1.2 petrol spark plug torque?

'The old days' when I was a ragged urchin working on them new-fangled steam ships. Or more accurately, when I could only afford ropey, old vehicles and had to maintain them myself. At least I didn't have to deal with on-board diagnostic computers, everything could be fixed with a hammer & a bit of baling wire.
My motto 'when in doubt, give it a clout'.
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Old 06-07-2019   #13
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Re: 1.2 petrol spark plug torque?

Quote Originally Posted by t0neloc View Post
'The old days' when I was a ragged urchin working on them new-fangled steam ships. Or more accurately, when I could only afford ropey, old vehicles and had to maintain them myself. At least I didn't have to deal with on-board diagnostic computers, everything could be fixed with a hammer & a bit of baling wire.
My motto 'when in doubt, give it a clout'.
You were lucky. When I were a lad...
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Old 06-07-2019   #14
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Re: 1.2 petrol spark plug torque?

Quote Originally Posted by KPat View Post
You were lucky. When I were a lad...
Yer all whipper snappers........
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