Seized spark plugs

Post by **mgcjag** » Thu Apr 23, 2015 7:53 pm

Hi All.....S2 4.2.....have a misfire that im trying to work through and tried to remove the plugs...they all really tight and i did not want to risk exerting too much force to remove them just incase i strip the thread.....have put some penetrating fluid aroud to soak overnight......my question will it be best to try to remove them with the head hot or cold...will try everything else to clear the misfire and possibly leave the plugs till the end of the summer, just incase one gets stripped....Steve

Durango2k · Post by **Durango2k** » Thu Apr 23, 2015 8:37 pm

Try when hot. Alloy expands, they should be looser then.

And do set the new ones when the head is cold.

I think in your case someone torqued them down in a hot head, so they're shrunk in place, somewhat.

Carsten

Gfhug · Post by **Gfhug** » Thu Apr 23, 2015 9:09 pm

And I suggest you use copper grease when refitting.
What is the correct torque for the plugs? It can be very easy to use too much.

Good luck with your problem Steve

abowie · Post by **abowie** » Thu Apr 23, 2015 11:23 pm

Plugs have a crushable sealing washer on them that stops combustion gases escaping; this will probably prevent any penetrating oil getting in as well.
Regardless, you need to get them out. If they are corroded waiting will just make them worse, so you may as well get on with it.
If you strip one you can get it repaired in situ so it's not ideal but not a big issue.
Might be worth talking to your garage in case they have a clever way of doing it.
Otherwise, if it were me I'd do it with the engine hot and use a looong extension bar. This way you aren't having to exert yourself much so you can turn it really smoothly; no jerking. You also want to make sure you keep the socket in line with the axis of the plug.
From memory plugs are only supposed to be done up to maybe 15ftlb but many people do still feel the need to do them up tight.

Post by **mgcjag** » Fri Apr 24, 2015 8:43 am

Thanks Guys...I actually fitted these myself new with copper grease by hand when cold and not too tight..always wary of a plug in an alloy head....this was about 2 years ago and have only done a few short runs and startups over winter.. (been busy doing up a new house ).will get it nice and hot and try again....Steve

Post by **mgcjag** » Sat Apr 25, 2015 10:39 pm

Hi All.....points were well pitted...suppriesd that the car was running with only a misfire...changed them and the condensor out for a Pertonix, and fitted a red rotor, & coil simple swap and the car started up straight away, checked with a strobe and timeing ok but still a slight blip can be seen with the timeing mark just blipping against the strobe flash...Checked out the carbs fuel level ok in the jets and all balanced.....So next to change the cap, leads.....went for a run to get the car nice and hot and still just the odd blip.........but still the plugs wont move with reasonable force......dont want to risk stripping the thread so think i will just sort the misfire, run the car for the summer and crack the plugs later in the year.....at best they will all come out, worst case strip threads and head will come off....Steve

christopher storey · Post by **christopher storey** » Mon Apr 27, 2015 10:11 am

Steve : keep squirting penetrating oil into the plug wells ( plus gas is still the best ) . It will probably eventually percolate between the washer and the plug body and thence down the threads . I would then attempt to remove them cold . This was always the advice for al2 heads in my more immediate youth - that is , 56 years ago when I first started playing with cars - and it always has to be remembered that they may already have been helicoiled, in which case considerations of differential expansion may not arise . In any event, I am not at all sure that the higher coefficient of linear expansion of al2 does not make the female threads grip the threads of the plug more tightly

Robert Hiland · Post by **Robert Hiland** » Mon Apr 27, 2015 11:27 am

The following information was submitted by a member of the Ottawa Jaguar Club.

Penetrating Oils Machinist's Workshop MagT recently published some information on various penetrating oils that I found very interesting. Some of you might appreciate this.

The magazine reports they tested penetrates for break out torque on rusted nuts. They are below, as forwarded by an ex-student and professional machinist. They arranged a subjective test of all the popular penetrates with the control being the torque required to remove the nut from a "scientifically rusted" environment

*Penetrating oils ........... Average torque load to loosen*
No Oil used ................... 516 pounds
WD-40 ..................... ... 238 pounds
PB Blaster .................... 214 pounds
Liquid Wrench ...............127 pounds
Kano Kroil .................... 106 pounds
ATF*-Acetone mix............53 pounds
The ATF-Acetone mix is a "home brew" mix of 50 - 50 automatic transmission fluid and acetone. Note this "home brew" released bolts better than any commercial product in this one particular test. Our local machinist group mixed up a batch and we all now use it with equally good results.

Note also that "Liquid Wrench" is almost as good as "Kroil" for about 20% of the price. Steve from Godwin-Singer says that ATF-Acetone mix is best, but you can also use ATF and lacquer thinner in a 50-50 mix.

*ATF=Automatic Transmission Fluid

As a side note, I have been using this mixture for a couple of years now, and have found that the Acetone does not dissolve with the ATF, so you have to keep shaking. Whereas lacquer thinner does mix, so I have been using a mix of 50-25-25. In storage keep the mixture sealed otherwise you lose the acetone and lacquer.This actually works well, power-steering fluid also works as well as trans fluid!

Rule of thumb ... allow to soak overnight for best results.

rolando38 · Post by **rolando38** » Mon Apr 27, 2015 1:19 pm

very informative and ...surprising !
I have to separate my old exhaust from the manifolds soon, wil definitely test the Acetone+ATF home mix !!

Post by **mgcjag** » Mon Apr 27, 2015 4:03 pm

Thanks all for the response.Cant jet Pluss Gas locally so just tried the..Acetone anf ATF mixed and soaking around the plugs.....note as stated the acetone and atf dosent mix well because of this cant see how the acetone will carry any oil into a thread.... will try to undo again tomorrow when cold...Plus Gas on order and will try this if the acetone dosent work.....Steve

rolando38 · Post by **rolando38** » Mon Apr 27, 2015 8:51 pm

I talked of your problem to a mechanic friend of mine and it seems that Copper grease chemically reacts with aluminium/alloy....might be the cause of the seizing
easy to say afterwards...I did'nt know either

Alty Ian · Post by **Alty Ian** » Mon Apr 27, 2015 10:26 pm

rolando38 wrote:I talked of your problem to a mechanic friend of mine and it seems that Copper grease chemically reacts with aluminium/alloy....might be the cause of the seizing
easy to say afterwards...I did'nt know either

It wont be a chemical reaction but an electrolytic one. Theoretically, dissimilar metals will start a corrosion cell and create some corrosion, but I must admit that is quite surprising though bearing in mind copper grease is supposed to prevent threads sticking.

vrracing · Post by **vrracing** » Mon Apr 27, 2015 10:59 pm

Might be helpful.

Simonpfhc · Post by **Simonpfhc** » Tue Apr 28, 2015 6:51 am

You should never use Copper Grease when threading steel into alluminium - as Ian has stated, it causes an electrolytic reaction and has the opposite effect of keeping the threads from seizing.

The best stuff to use is Opitmily Paste TA (or something similar). I discovered this as Porsche recomend this stuff when bolting their alluminium wheel bolts into the steel hub.

Keep the Copper Grease for steel in steel

However, I always thought that you should leave spark plug threads dry and never tighten much more than finger tight??

Cheers.

Gfhug · Post by **Gfhug** » Tue Apr 28, 2015 7:52 am

Simon, is this the stuff?
http://www.design911.co.uk/fu/prod12634 ... 004302000/

Post by **mgcjag** » Tue Apr 28, 2015 9:10 am

Hi all.....All plugs now out.......acetone mix was still poolrd around the plugs so not much could have got to the threads ......with the engine cold the plugs came out supprisingly easy.....Steve

Simonpfhc · Post by **Simonpfhc** » Tue Apr 28, 2015 9:24 am

Hi Gfhug,

Yes, that is the stuff.

Cheers.

rolando38 · Post by **rolando38** » Tue Apr 28, 2015 12:53 pm

good news Steve
Sometimes you need to let things cool down a bit...

Gfhug · Post by **Gfhug** » Wed Apr 29, 2015 8:30 am

Glad to hear you've got the plugs out Steve.

It would be interesting to get a feel for who does or doesn't use copper grease or optimol paste.
From NGK (http://www.ngkntk.co.uk/index.php/techn ... ng-torque/)
NGK does not recommend the application of lubricant to spark plug threads as the resultant reduction of frictional forces at the thread faces will render the torque charts inaccurate and over tightening could occur

And we can see their recommended torque settings of 25-30 Nm, or 18-21.6 lbs ft in old money.

Have always been told to use copper grease on aero-engines and when the carbs were set up last year the mechanic used copper grease (on the plugs not the carbs, before anyone comments

)

Post by **mgcjag** » Wed Apr 29, 2015 8:48 am

HI all.....lets end this post and I will start a new one on anti sieze grease.... Steve

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