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RichieW

Spark Plug Thread Repair

14 posts in this topic

Hi folks,

My stepdaughters 99 fiesta ejected one of the spark plugs the other day. Does anyone know anything about the thread repair kits? More specifically, which one to buy as there are different sizes! I bought4 new spark plugs in any case and when I tried to tighten the plug in to the 2nd port it tightened down and then just started to turn.

Any advice would be greatly appreciated and I am comfortable with re-tapping if necessary.

Thanks!

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Sorry, spark plugs are NGK 0005 and the car is a 1.25 petrol fiesta LX, thanks again folks

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You will need to get a helicoil thread repair kit. The biggest problem being the material removed when drilling and tapping ends up in the cylinder

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Ah right, not too worried about the bits. Are you able to tell me which kit to go with? Not too sure about the different sizes and I have been unable to find any size guides..Thanks for the quick reply

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Ah right, not too worried about the bits. Are you able to tell me which kit to go with? Not too sure about the different sizes and I have been unable to find any size guides..Thanks for the quick reply

If I had a spare spark plug I would measure it for you but I think the thread size your looking for is M12 x 1.25mm

Your other option is to try and get an insert as helicoil a often come out when removing the plug

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I checked the measurements for the spark plug and it said the outer thread size was 14mm. And what do you mean by an insert? Are they similar to helicoils but without the bit that you have to break off due to having a collar? Or am I being silly?

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I checked the measurements for the spark plug and it said the outer thread size was 14mm. And what do you mean by an insert? Are they similar to helicoils but without the bit that you have to break off due to having a collar? Or am I being silly?

I thought M14 at first but then I had a thought that they were M12 :lol:

Yeah your correct, you tap out the head to take the insert, screw it in until the collar is flush with the head and then put your plug in. Chances are it will come out with the spark plug but it should be easy enough to replace unlike a helicoil where you would need a new one.

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Wicked mate, so I need A M12 repair kit then? They do them on eBay quite cheap! And it's definitely cheaper than taking it anywhere to get it done (200 - 500)!!

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Wicked mate, so I need A M12 repair kit then? They do them on eBay quite cheap! And it's definitely cheaper than taking it anywhere to get it done (200 - 500)!!

You will need M14 x 1.25mm

You will need to try and gauge what length of insert you need too.

Yeah there are plenty kits on ebay, helicoil and insert type.

It would be more work but would taking the head off be an option? Would save all those filings going down the cylinder and would mean your not trying to do all this work on the car

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Last thing you want is metal falling into the bore. It will just score the liner.

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How much more work are we talking and do I need other specialist tools?

I really appreciate all the help guys, cheers!

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Hi Folks,

Ok, so I've got the thread repair kit.. Are the heli-coils supposed to be able to screw on to the spark plug at this stage? I ask because they don't. They kinda slide over the spark plug thread. This, for me, says one of two things. Either the 'tightness' of the heli-coil will increase once it has been inserted in to the head, or the M14 size kit that I bought is actually the wrong size??

Can anyone offer some advice on this? If I go any further with the repair then I won't be able to send the kit back so I need to be sure!! :unsure:

Thanks in advance!

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Specs for sparkplug

Catalogue of Auto Parts / NGK 0005

Car Part NGK 0005 Spark Plug

Manufacturer NGK Number 0005 Description Spark Plug Spanner Size 16,0 mm Outer Thread [mm] 14,0 Thread Length [mm] 25

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Thanks for the specs Charlie!

So, just so we're 100% clear, the kit I've got should be the right one and the fact that the helicoil slides over the spark plug thread rather than screw on should change once it has been inserted in to the head??!

Not trying to be rude or funny here so please bare with me!!

I'll keep you all posted on my progress when I get started on it :)

Thanks again for the help!

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