Technical 1.2 8V spark plugs are falling out

[Pugglt Auld Jock]

Not quite the same problem, but I cross threaded one a while back. My local man fixed this and charged 1 hour which seems pretty reasonable to me. Torque figure he quoted me was 18 somethings which is not a lot. If they have all been over done and the threads stripped Its a head off job I agree. New plugs havbe compressible washers so trying new plugs might help?

Our dear old friend John Haynes recommends 18lbsft (25nm) which is a decent figure for the likes of a M8 bolt to give you some idea.

As jrk points out above your average DIY quality 1/2" drive torque wrench will not be accurate at that sort of figure. In fact most traditional torque wrenches are only truly accurate at mid range settings. If you want to buy a device which has a large range but is still accurate near the upper and lower limits of it's scale I can recommend a digital wrench which works via a strain guage rather than a mechanical mechanism which will be affected by friction and cleanliness and/or how it's stored and calibrated. I bought one of these a couple of years ago:https://www.machinemart.co.uk/p/040215238/?awc=3131_1679589983_961cdb4e34a6c8c0d725f9a1bee939b5 and I must say it works very well indeed. It's one failing is that it is quite deep once assembled onto a socket and power bar. Fine for doing heads but not so easy in restricted areas like timing belts. When I first bought it my old mechanical Britool torque wrench had just been calibrated (you do all know that mechanical torque wrenches should be periodically calibrated don't you) and I connected it to the electronic torque adaptor so I could check what the electronic device thought of several setting on the Britool. I did it at roughly a third, half and two thirds full scale and the two agreed exactly so I think the digital adaptor is pretty accurate. Now I use the digital adaptor to periodically check my mechanical torque wrenches against and only send one away for calibration if it disagrees with the electronic device.

Edit. What's quite nice about the electronic adaptor is that you can set it to beep at a set figure, just like a conventional torque wrench which "clicks" but you can also set it to display the torque being applied numerically on it's wee screen. I can see this will be very useful if/when I have to do the water pump/thermostat housing on the Ibiza which has to be held at a set torque figure as the securing bolts are tightened so that the drive belt to it is properly tensioned. A conventional "click type" torque wrench couldn't do this, although the old "spring beam" type favoured by my American friend would.

 

[koalar]

Our dear old friend John Haynes recommends 18lbsft (25nm) which is a decent figure for the likes of a M8 bolt to give you some idea.

Torque figures are clean and dry threads only

You can’t judge by feel

New plugs are easier and safer as you can feel the new washer crush

Here’s fiats take on torque for 14mm plugs in the panda

 

[vexorg]

Torque figures are clean and dry threads only

You can’t judge by feel

Yes you can, I've never used a torque wrench for plugs and never had an issue. Wind it in by hand, then use the ratchet slowly and you feel the comprssion washer resistance, it stops when fully compressed then a little tweak (no more than a few degrees) and you're good.

 

[koalar]

Yes you can, I've never used a torque wrench for plugs and never had an issue. Wind it in by hand, then use the ratchet slowly and you feel the comprssion washer resistance, it stops when fully compressed then a little tweak (no more than a few degrees) and you're good.

Correct

But Isn’t that exactly the same as my original post if all of it is quoted

“New plugs are easier and safer as you can feel the new washer crush”

However If the original plugs are old the washer doesn’t crush and 14 ft lbs i(1.2 with anti seize) is pretty impossible to judge by feel.

https://www.ngk.com/ngk-plug-torque-settings

 

[Pugglt Auld Jock]

Yes you can, I've never used a torque wrench for plugs and never had an issue. Wind it in by hand, then use the ratchet slowly and you feel the comprssion washer resistance, it stops when fully compressed then a little tweak (no more than a few degrees) and you're good.

I think it's very much a case of having the "feel" and that only comes with experience. It's different whether it's a crush washer type or taper seat. Of course it's quite likely, especially if the vehicle is an older one, that someone like me will have put something like copper grease on the threads. This will have coated the threads in the head thus rendering the use of a torque wrench to achieve the correct tightening very questionable and maybe dangerous as you might over tighten and cause thread damage inadvertently. I was taught in college and on the shop floor to spin the plug in by hand until it seats and only then applying the wrench. I've had problems when the person who was there before me has caused thread damage but I honestly can't remember ever myself causing thread damage by cross threading a plug. If it doesn't go in smoothly by hand you just don't try to wind it in any further. After you've done it day in day out for years you just get to know what feels "right".

However, having said all that I've read that the electrode positioning in these modern small turbo petrols is a critical factor in reducing the tendency for them to suffer Low Speed Pre-Ignition. Apparently it's all to do with the way the flame front propagates in relation to the way the side electrode is positioned in the combustion chamber and particularly in relation to the valves? Sounds like a whole load of BS to me but I read quite a lengthy article somewhere about it. It seems that these plugs are very carefully made with their side electrodes very precisely positioned in relation to the start of the screwthread so that if a torque wrench is always used the electrode ends up pointing in the desired direction when the plug is properly tightened? If this is true I can completely see the need to use a torque wrench and always assemble with dry threads. I'll be doing them that way on the Ibiza from now on but will probably just continue to instal plugs on the other family cars as I've always done.

 

[vexorg]

I'm not sure you can correctly guarantee then angle based on torque, if it was that critical then it should have a mark to align to the head. It does sound like nonsense, a bit like most of the spark plug featuresyou hear about.

 

[jrkitching]

It does sound like nonsense, a bit like most of the spark plug features you hear about.

I remember having a discussion about indexing the plugs about 10 years ago.

It can get you a small amount of extra power/efficiency but the gains are minimal. It's the sort of thing folks preparing drag racing engines worry about (tiny fractions of a second can be important to such types), but the consensus view at the time seemed to be that it wasn't really relevant to a 1.2 FIRE in normal use.

If you want to delve a little deeper into the subject, google "spark plug indexing washers". Basically you mark the position of the electrode on the outside of the plug so that you can see where it ends up when correctly torqued, then remove and replace after fitting a replacement washer of just the right amount of differing thickness to get it exactly (or at least closer) to where you want it to be.

At that time, I did check it with a new set of NGK iridiums and found that 3 of the 4 plugs were at least close to the theoretically ideal position once torqued up. I didn't bother doing anything further about this, and the car ran perfectly well.

For the vast majority of us, I'd agree that this is a red herring.

 

[varesecrazy]

I remember having a discussion about indexing the plugs about 10 years ago.

It can get you a small amount of extra power/efficiency but the gains are minimal. It's the sort of thing folks preparing drag racing engines worry about (tiny fractions of a second can be important to such types), but the consensus view at the time seemed to be that it wasn't really relevant to a 1.2 FIRE in normal use.

If you want to delve a little deeper into the subject, google "spark plug indexing washers". Basically you mark the position of the electrode on the outside of the plug so that you can see where it ends up when correctly torqued, then remove and replace after fitting a replacement washer of just the right amount of differing thickness to get it exactly (or at least closer) to where you want it to be.

Its a FIRE engine.. just line them up when you change the HeadGasket


In all seriousness..
WASHERS... ??? If you were worried about such 'gains'..

Buy boxes of 10 plugs..and select 4 of the ones where the electrode arm is in the same spot on each plug.. (relative to the thread start..

Rather than setting 4 accurately gapped plugs at differing heights from the crowns

 

[koalar]

I think it's very much a case of having the "feel"

Feel can be misleading. The 1.1 is 50% tighter than the 1.2 for some reason.

and that only comes with experience. It's different whether it's a crush washer type or taper seat. Of course it's quite likely, especially if the vehicle is an older one, that someone like me will have put something like copper grease on the threads.

The finish on NGK plugs is a trivalent plating. The coating acts as a release agent and is corrosion resistant

This will have coated the threads in the head thus rendering the use of a torque wrench to achieve the correct tightening very questionable and maybe dangerous as you might over tighten and cause thread damage inadvertently. I was taught in college and on the shop floor to spin the plug in by hand until it seats and only then applying the wrench. I've had problems when the person who was there before me has caused thread damage but I honestly can't remember ever myself causing thread damage by cross threading a plug. If it doesn't go in smoothly by hand you just don't try to wind it in any further. After you've done it day in day out for years you just get to know what feels "right".

Spark plugs deserve a thread of there own

Getting seized one out
Temperature rating altered by anti seize
Only torque on a cold engine and so on

 

[jrkitching]

Spark plugs deserve a thread of there own

There have been several in the past; this is perhaps the most comprehensive. But it's a lot of work to read through it all and separate out the wheat from the chaff; condensing this into an "all you need to know about plugs" guide would be most helpful.

Getting seized one out
Temperature rating altered by anti seize
Only torque on a cold engine and so on

All excellent points, and all topics which should be included in any guide.

 

[DaveMcT]

Anti sieze will change the temperature rating and that's important with today's fuels. But it wont matter on a 50 bhp per litre two valve engine. It won't even matter on a 100bhp per litre two valve engine. What's more important is the ability to extract the plugs when the time comes. Spark plugs in car engines are well protected from road salt, water and other kak that hits the vehicle. Bikes and some cars will be different. Those that don't need the stuff are better without.

 

[Pugglt Auld Jock]

I find all this very very interesting and I enjoy reading everybody's experience and advice. However I'm sitting here with my first cup of tea of the day and thinking:- All these years I've been messing about with cars and I really couldn't say how many spark plugs I've changed both for myself and in customer vehicles, Must be many thousands? and either I myself, a family member or the customer has just got into the car and driven away until the next time the plugs need renewed. I could probably count on my fingers the number which have had a plug related problem, especially one related to installation, so I think we're all getting very "excited" unnecessarily over what is, mostly, a very simple everyday task. I'm sure 99% of the chaps on the shop floor don't even give it a thought!

 

[DaveMcT]

It's amazing how many DIY mechanics fail to realise when they have a thread crossed. Whatever you are fitting, screw it in by hand at least for a couple of full turns (not just a couple of flats). If it's too stiff, then investigate and find out why. Really? How hard can it be?

Panda 1.2 spark plugs are angles so can be awkward. Use a decent quality plug spanner socket. Absolutely DO NOT use one of those silly hinged type available at all "good" motor shops. Get a nice long socket that will work on all engines and you'll never need another one.

 

[Pugglt Auld Jock]

It's amazing how many DIY mechanics fail to realise when they have a thread crossed. Whatever you are fitting, screw it in by hand at least for a couple of full turns (not just a couple of flats). If it's too stiff, then investigate and find out why. Really? How hard can it be?

Panda 1.2 spark plugs are angles so can be awkward. Use a decent quality plug spanner socket. Absolutely DO NOT use one of those silly hinged type available at all "good" motor shops. Get a nice long socket that will work on all engines and you'll never need another one.

Yup. I suppose there is the odd occasion when a universal joint could be useful but a magnetic plug socket with a choice of several lengths of extension and a ratchet or "T" handle would be my preferred choice of weapon. I never had a magnetic plug socket until recently - long after I stopped earning my living with the spanners - and I can thoroughly recommend one. Much nicer to use than the older type I had with the rubber washer inside which falls out when it gets older! You can buy a very adequate set of two on Ebay for around a tenner which will cover the two most popular hex sizes.

 

[3234dmtr]

Years ago, a friend of mine struggled to get a spark plug removed out of his -hm- 1983 Opel Kadett D ( Vauxhall Astra I believe? ). He used a drill to get it out and guess what, the mounting hole got messed up. We ended up at an engine revision company who threaded a helicoil in the head, all done within 15 minutes. Engine outlasted the car which eventually ended up in the scrapyard, more rust/corrosion then bodywork.... About handling sparkplugs, I personally use deep dedicated sparkplug nuts and have these in different sizes. Unscrewing with the tools sitting correctly without play, mounting ALWAYS by hand until it doesn't go any further. And I always use a torque wrench, torqueing down to manufacturers specification. Talking about sparkplugs, those aren't even half that difficult compared to GLOW plugs on diesel engines.

 

[koalar]

I find all this very very interesting and I enjoy reading everybody's experience and advice. However I'm sitting here with my first cup of tea of the day and thinking:- All these years I've been messing about with cars and I really couldn't say how many spark plugs I've changed both for myself and in customer vehicles, Must be many thousands? and either I myself, a family member or the customer has just got into the car and driven away until the next time the plugs need renewed. I could probably count on my fingers the number which have had a plug related problem, especially one related to installation, so I think we're all getting very "excited" unnecessarily over what is, mostly, a very simple everyday task. I'm sure 99% of the chaps on the shop floor don't even give it a thought!

Correct

It’s the same with a lot of things

Easy if you do them day in day out

Correct

We tend to over complicate things

Correct

For such a simple thing, it’s very easy to get wrong and cause annoying damage, cross threading, under and over tightening along with thread pick up due to seized plugs removed hot are fairly common

When I had the head off mine all 4 were damaged on the first few threads and there was some thread pick up.

On an open forum giving advise is alway difficult because the experience of the reader varies as does there access to equipment and tools available.

In an ideal world you unscrew the spark plug and screw in a new one by hand and tighten down to torque. SIMPLE. But due to lack/poor maintenance it does not always go to plan