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Spark Plug Change Issues

Logikal

By Logikal,
in General Maintenance

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Logikal Collaborator

Logikal

Posted
Posted

Hi all,

Have a bit of a drama with changing my spark plugs and I have a feeling something extremely bad has happend.

Story goes, last Saturday I bought some new spark plugs (NGK BKR6ES) and tried swapping them around with my old plugs (NGK Iridiums that were put in by Gavin Wood Autotech on the Gold Coast).

I cleaned the area with compressed air and used a cotton bud to take out any extra debris. All was going well until I tried replacing spark plug number 5. It went in easy for the first 3 turns then started to resist being screwed in. I didnt push any further - took the plug out and checked the thread. Nothing was wrong with it. I then looked at the old plug to see if the thread had been damaged on that one - no damage. So I left it for the week.

Came back this afternoon. Had an idea to use some engine oil to lube the thread and see if that screwed in anymore.

Same resistence after the third turn - only when I took the new plug out this time - there was slivers of metal that came out in the new plugs thread :D I then put a cotton bud down the plug hole to see if anything else would come out - a tiny bit more of metal came out :(

Obviously this is a very bad sign. So I'm stopping all work on my car as of now and calling Marty on Monday. I need some opinions from you guys/girls on how serious this may be. For example: Do I need a new head? or is there anyway chance of saving the current head on my engine?

Any helpful comments would be great. Cheers.

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black_gtst Proficient

black_gtst

Posted
Posted

hmmm that a bit of a boo boo! i dare say pulling the head off and re-tapping the thread will be the way to fix. few hours involved though. As for new head, i doubt it man its just a matter of cleaning up the thread. im sure your not the first one this has happened 2!

R33S2 Grand Master

R33S2

Posted
Posted

Its hard to say without looking at it, but you wont need to replace the head, just retapping the thread will fix it, the worst that can happen is it may need a helicoil but i doubt it if you stopped when it got too tight.

Fry_33 Proficient

Fry_33

Posted
Posted

I had a cross-threaded spark plug in my old VK commodore. One of my work mates at that time was a mechanic and carefully used some thick grease on the tap and any swarf created was caught by the grease.. Well being realistic, the majority of it I guess, no way of really knowing though. TIt was all good after that. Just an alternative that may save you some time. Good Luck

black_gtst Proficient

black_gtst

Posted
Posted
Thanks for you reply black_gtst.

So re-tapping the thread should fix the issue even if it seems like the existing thread is breaking to pieces?

i would doubt the origionl thread would be breaking apart but i guess anything is possable. if you are confident doing it yourself pull head off and take it 2 someone. worst case they will drill it out, put a sleeve in it ans then tap a new thread. a custom engineering place should be able to sort it out for you. as i say bit of stuffing round but prob no need for a new head.

hope this helps you out, im sure someone that has had the same problem will post up!

brett

halomansion Contributor

halomansion

Posted
Posted

ye its terrible when something like that happens.at least you were careful etc.it is usual to retap a thread but get someone good to do it so you get a good thread.it might leave some debris in engine from retap so perhaps consider that.dont know what caused it to thread.probably just a bit of wear and tear.i think some times the plugs may vary a bit and it is very unfortunate.

nuclear_skyline Mentor

nuclear_skyline

Posted
Posted

I watched one of the mechanics where i used to work fix a similar issue.

Step one: find the appropriate tap for the thread.

Step two: smother the tap and thread in the head in thick grease.

Step three: gently clean the thread by running the tap through.

Step four: using ear cleaners, clean the thread out and make sure its clean.

He then did something I thought could be useful in all sorts of circumstances.... He had a small vaccum line (like the ones all over the engine bay). He tapped it up to the end of a vaccum cleaner and then proceeded to vaccum the cylinder out...

Step Five: Vaccum the cylinder out!

The car that i watched it on went fine... and the plug threaded in nice and easy.

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