Cross threaded spark plug

[jamesandtheopenroad]

Morning.

Wanting to check the conditions of my plugs and going to remove the plug on number 1 cylinder can feel from the off that It's been cross threaded - not by me I hasten to add.

So, how do I go about removing it to do the littlest damage?

Thanks

[kevtherev]

nothing you can do
unless it doesn't unscrew
then yuou have to pull and unscrew

[ghost123uk]

Agreed, just use a decent plug socket and go for it. Mind you, if it is screwed in far enough to seat properly I bet it isn't cross threaded, but just bliddy tight. I would unscrew it "back and forth" style as you are undoing it. Half a turn out, quarter of a turn back in, then 1 turn out and half a turn back in kind of thing. This will ease it out of it's threads with less force involved.

When you have got it out, take the others out too. Then put a new plug into a known good cylinder and do it up until it is "just" seated. Then undo it two full turns and try to wobble it. Make a mental note of how much it wobbles (won't be much). Then do the same with the suspect one. If it wobbles lots more than the other, then the thread is likely damaged. I had one with very loose threads (on a previous engine to the one I have now) and my local T25 friendly garage successfully helicoiled it in situ. I was delighted with that (after being pretty worried )

[Ian Hulley]

A good advert for why you should start these things with your fingers and NEVER a ratchet let alone a drill driver.

[ghost123uk]

Very true

And sump plugs too.

[jamesandtheopenroad]

Thanks guys - will look at it over the weekend.

[Oldiebut goodie]

A good advert for why you should start these things with your fingers and NEVER a ratchet let alone a drill driver.

Always used to use a piece of hose - especially when the plugs were deep.

[CovKid]

I assume you mean pushed on to end of the plug rather than inserted into some convenient orafice for comfort purposes.

[Oldiebut goodie]

Nothing wrong with colonic irrigation!

[Plasticman]

depends on who you are irrigating, in fact it would be a deal breaker
err back to it, this is onre of the reasons i always run a tap down threads and likewise always start brake nipples by hand .too easy to Xthread.
whats been said above makes as much sense as can be and if its stripped then not too bad to repair
mm

[jamesandtheopenroad]

Hello again

Right, spark plug out, cleaned up , there was a bit of cross threading and some of the thread on the egine has gone but the spark plug goes back in true. Put in finger tight and nipped up with a socket.

However, upon cranking the engine over by hand, I heard air escaping and sure enough, with some WD40 around the plug base, air is escaping on the up stroke, which I'm guessing means less compression on that chamber.

The plug itself is good and was an NgK lpg specific one so I'd like to save it - can I use another washer or o-ring to seal it in a bit better?

[Dazco]

I would have thought if it was leaking once nipped up its gonna leak no matter what. Might be worth trying another washer or possibly a thin smear of exhaust putty on the thread, but it needs sorting properly .

[jamesandtheopenroad]

Bum.

[Ian Hulley]

PTFE tape round the thread ? Got to be worth a go while you save up for a helicoil ?

Ian

[jamesandtheopenroad]

PTFE tape round the thread ? Got to be worth a go while you save up for a helicoil ?

Ian

Yeah, I did think that Ian, but thought it might melt. But if it's good enough for my sump plug then ...

Also though about a bead of high temp gasket sealant around the seating edge of the washer. Might try both.

I take it then that helicoils are damned expensive. Or is it the labour to have it done?